- externally adds new function lib3mf_reader_getwarningutf8
- internally uses UTF8 strings for all warnings

Source:
https://en.wikipedia.org/wiki/UTF-16#U+0000_to_U+D7FF_and_U+E000_to_U+FFFF

* First working UTF8-implementation

* Remove unused code im xml-reader

* Remove plenty of unused 'GCC'-code

* Port VS unittests to gtest

* Make UTF8-changes and UnitTests compile on linux

* Fix MAC build

* Address some TODOs

* Remove broken COM-functionality

* Change some more interfaces to UTF8

* Remove unsused includes and NMR_COM_NATIVE flags

* Up the version number

* Remove ATL from examples

* Remove unused OPC-headers

* Make NMR_COM_NATIVE settable on the command line

* Negate offset when ZIP_SOURCE_SEEK from SEEK_END 

custom_zip_source_callback from the zip library where the cmd is ZIP_SOURCE_SEEK and whence is SEEK_END specifies a negative offset.  pImportStream takes an unsigned positive value to indicate the distance to seek back.  The value must be negated between the two APIs.

* Assume unsigned argument for seekFromEnd

The API for CImportStream and CExportStream only allows unsigned input.
This commit handles this consistently in all seekFromEnd-functions
and adds some exceptions in custom_zip_source_callback.

* Support zip seeking backward from the current position.

* Update version

For linux, osx
Add build-status to README
Register tests for CTest

Which is correct according to the slices-extension

Add API functions
- lib3mf_texture2d_settilestyleuv
- lib3mf_texture2d_gettilestyleuv
Refactor reading/writing of tilestyles
Update Tests, SDK documentation and SDK-examples

Instead of copiiing the full input stream into memory.
This decreases the memory consumption of lib3MF on import by the size of
the compressed zip-file.
The speed of the import is higher for files with large attachments (e.g.
large textures, binary blobs) and not slower for "regular" XML content of
3MFs.

- Correct zip64 End Headers
- Correct zip64 offsets
- Update Version Number

Includes example in SDK, UnitTest, and documentation

- Make progress more granular
- Add UnitTest_ProgressCallback
- Add intra-model updates
(their actual progress is monotonically increasing, but actually made up.)

Correct according to Slice-extension, v1.0
"The <polygon> element contains a set of 1 or more <segment> elements to describe a 2D contour.", p19.

+ Updated micro-version number

Add some links, describe build process

Comes with the added benefit of removing the gmoch-projects from
the VS-studio projects-generated by cmake.

to have three levels of versions.

make UNIX build lib3MF.so/dylib instead of liblib3MF.so/dylib