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

All former copyright holders (Microsoft Corporation, Autodesk Inc. and
netfabb GmbH) have contributed to lib3MF and continue to contribute to
lib3MF as members of the 3MF consortium.

The binary pakage lib3MF_sdk.zip now contains the LICENSE file.

* 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

* 32 bit builds need explicit cast when converting uint64 to size_t

* 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

* Speed up OSX-builds

By not auto-updating brew

* Comment Travis CI-configuration

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

Which is correct according to the slices-extension

Use public URL instead of SSH URL to avoid authentication errors when pulling from googltest.

See this for more details.  https://salferrarello.com/git-submodule-fatal-read-remote-repository/

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

Correct according to Slice-Extension, v1.0, Chapter 3, Diagramm
or look at the XML-schema which notes minoccurs="2" for the <vertex>-element