Add initial Meson build file

Fix #567 in writing real values in different locales

The output of snprintf might produce ',' separators for decimal places if
certain locales are set. This commit moves the converversion from ',' to '.'
to correct place. Otherwise an additional ".0" might be appended.

Allocate the proper memory for formatString. Fix a warning with gcc 7.1

/root/firefox-gcc-last/toolkit/components/jsoncpp/src/lib_json/json_writer.cpp:139:16: note: using the range [-2147483648, 2147483647] for directive argument
/root/firefox-gcc-last/toolkit/components/jsoncpp/src/lib_json/json_writer.cpp:146:10: note: 'sprintf' output between 5 and 15 bytes into a destination of size 6
   sprintf(formatString, "%%.%dg", precision);
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix QNX build: QNX defines sprintf under the std namespace. 

Refactor authorship information for more technical accuracy.

Google advises its employees to add Google Inc. as an author, but that hasn't
been done yet and would be super inconvenient. So instead I've refactored the
file to refer to "The JsonCpp Authors", which are listed in the AUTHORS file.

The AUTHORS file itself is generated via:

    git log --pretty="%an <%ae>%n%cn <%ce>" | sort | uniq

Plus the addition of "Google Inc." as a copyright author. (Google owns the work
of anyone contributing from an @google.com address, for example.)

The list contains some probable duplicates where people have used more than one
email address. I didn't deduplicate because -- well, who's to say they're
duplicates, anyway? :)

Including instructions in how to use jsonCpp with conan

Also added the badge to the conan package.

Related to issue #564

Fix V815:Decreased performance

Optimize Value::isIntegral() method

Fix warning issue with gcc flags.

closes #586

Worst case called modf() twice

FIx cmake build.

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

Fix crash issue due to NULL value.

README: Give some love

Using full paths is more versatile. The current solution
breaks when specifying an absolute path for CMAKE_INSTALL_INCLUDEDIR
which is an otherwise supported option by CMake's GNUInstallDirs.
CMake does not support Autoconf-style ${prefix}-pseudo variables,
hence trying to emulate the behaviour gains us nothing and breaks
providing absolute paths to CMAKE_INSTALL_LIBDIR.

Null value in Value constructor will crash strlen(). Avoid crash with JSON_ASSERT_MESSAGE

std::min<unsigned>, for VS2015

fixes #565

fixes #565

See #497, bottom comment.

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.

Replace current install variables with GNUInstallDirs

* The GNUInstallDirs module is more idiomatic and supported by
  Kitware upstream, whereas the current directories are not
  standardised across CMake-using packages. Using CMake native
  mechanisms is better than reinventing the wheel, as it makes
  using the build system more uniform across the ecosystem
* Use CMAKE_CXX_STANDARD to force C++11
* Require CMake 3.1.0 at a minimum
* Fixed lower/UPPERcase format for function/macro calls
* Fixed indents by replacing tabs with 4 spaces

Removed a static variable used to contain the current recursion depth in json_reader.cpp

Renamed JSONCPP_STACK_LIMIT to JSONCPP_DEPRECATED_STACK_LIMIT to stress that usage of this macros assumes old interface.

Add pragma pack directive

resolves #458

Related to https://github.com/open-source-parsers/jsoncpp/issues/458

Removed a static variable used to contain the current recursion depth of Reader::readValue().  The number of elements in an internal container Reader::nodes_  is used instead.  It is correct because any recursive call of Reader::readValue() is executed with adjacent nodes_.push()  and nodes_.pop() calls.  
Added the option to change the allowed recursion depth at compile time by defining a macro JSONCPP_STACK_LIMIT as the required integer value.

Clarify code for value type return