* ENH: Prevent cmake in source builds

Building directly inside the root of the source tree
can cause problems where the build intermediate files
overwrite or conflict with the intended source code
files.

This modification identifies this problem and
issues failure messages and suggestions to over
come the problem with more robust build suggestion.
Co-authored-by: Jordan Bayles <jophba@chromium.org>

* BUILD_TYPE corresponds to Release/Debug
   but LIB_TYPE corresponds to shared/static.

* Add support to build shared, static and object lib at the same time.

Commit aebc7faa added version checks for CMake compatibility. In reality,
only the add_compile_definitions need the check - add_compile_options
itself has been supported since 3.0. Tested and confirmed built
successfully with CMake 3.8.0.

Since CMake has subdirectory variable scope, unilaterally set the
CMAKE_CXX_STANDARD variable to use C++11. This covers cases with the
library being included externally, both in cases of only C++98 being
specified, as well as later versions being specified (since the
CXX_STANDARD itself isn't a library dependency, only the PUBLIC
target_compile_features on jsoncpp_lib). The previous direct check for
C++98 is handled by requiring C++11 on this library; should the
compiler being used not support C++11 then CMake will issue an error.

As of CMake 3.0 with CMP0042, MACOSX_RPATH is enabled by default.
Since the validated version used by jsoncpp is later than 3.0,
this is already covered.

The more general CMake way to handle library suffixing is to set
CMAKE_<CONFIG>_POSTFIX, so setting the Debug output suffix name should
be more correctly done by the caller or CMake configurer by setting
the desired value in CMAKE_DEBUG_POSTFIX.

* Prevent cmakelint warnings

Use 4 spaces for indent, no tabs

* Use ccache right

fix indents too at CMakeLists.txt

* Modernize meson.build

* Make tests optional
* Use `files()` for quick sanity checks

* Bump version to 1.9.3

* Bump SOVERSION, as some functions were removed
  and structs were changed, as determined by
  libabigail.

* Add option JSONCPP_WITH_EXAMPLE

Allows to conditionally build examples as
it has been done for tests.  Useful for packaging.

* Do not build example by default

We desire for jsoncpp to compile and be readily available
with older  versions of cmake.  The use of newer cmake
commands requires conditional statements so that older
strategies can be used with older versions of cmake.

Resolves: #1018

* update example directory

* modify some compile error.

* update with clang-format

* update

* update

* add_definitions("../include/json")

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Wed Jul 10 21:26:16 2019 +0800
#
# On branch code_example
# Your branch is up-to-date with 'origin/code_example'.
#
# Changes to be committed:
#	modified:   example/CMakeLists.txt
#

* change CMakeLists.txt

* update streamWrite.cpp

* update

* Update readFromStream.cpp

* fix typo

* Cleanup versioning strategy

Currently, versioning is a mess. CMake and Meson have seperate build
version number storage locations, with no way of knowing you need to
have both. Plus, due to recent revisions the amalgamate script is broken
unless you build first, and may still be broken afterwards.

This PR fixes some issues with versioning, and adds comments clarifying
what has to be done when doing a release.

* Run clang format

* Update SOVERSION....

This reverts commit 12325b81.

* Cleanup versioning strategy

Currently, versioning is a mess. CMake and Meson have seperate build
version number storage locations, with no way of knowing you need to
have both. Plus, due to recent revisions the amalgamate script is broken
unless you build first, and may still be broken afterwards.

This PR fixes some issues with versioning, and adds comments clarifying
what has to be done when doing a release.

* Run clang format

* Update SOVERSION....

Older versions of cmake, according to documentation:
https://cmake.org/cmake/help/v3.5/command/if.html , do not know
VERSION_LESS_EQUAL, just VERSION_LESS.

This leads to errors:

CMake Error at somewhere/jsoncpp/CMakeLists.txt:18 (if):
  if given arguments:

    "3.5.1" "VERSION_LESS_EQUAL" "3.13.1"

  Unknown arguments specified

Resolves: #866

1) Improve travis build script for use outside travis.
   Allow the script used for CI builds to also be used
   locally in a similar manner to the CI use of the scrips

2) Add ctest compatible testing and CDASH support
   Report testing and building results to
   https://my.cdash.org/index.php?project=jsoncpp

   NOTE: The new ctest infrastructure is not yet robust on winodws
         Do no yet enable the new features for running test with ctest
         on windows platform.  The previous behaviors are maintainted,
         but enhance test reporting from windows is not yet supported.

3) Add a cmake coverage testing option
   Ensure that cmake builds on linux are tested.
   Ensure that code coverage is reported.

4) Move conditional environment checking into the matrix
   Avoid multiple places where conditional logic is used to
   change compiler behavior.  As more test environments are
   created fromt the travis.yml matrix, all settings should be
   obvious from that one location.

5) Tests with known regressions from the jsonchecker are suppressed
    Tests that are known to pass with jsoncpp more lenient
    syntax enforcement are exluded from tests in test/runjsontests.py

Allow configuring without cmake policy developer warnings
for a range of cmake versions.

This prevents the need to explicitly enumerate every new
policy for each new cmake version.

===

Moved setting of the CMAKE_CXX_STANDARD to before the project()
directive.

The project directive in cmake 3.1 has a builtin
mechanism for providing consistent versioning
in a package.

Ancient CMake versions required upper-case commands.  Later command names
became case-insensitive.  Now the preferred style is lower-case.

Note that cmake is deprecated, but we keep it in-sync manually for now.

Soon, I hope to drop the cmake stuff and let meson handle
the version numbers.

FIx cmake build.

PR for - https://github.com/open-source-parsers/jsoncpp/issues/586
Separating the default options for compiler flags.

Plus some other build-related changes. I don't think there is anything
functionally different from 1.7.7, or even any binary incompatibilities, but
the cmake change is significant.