The library uses FreeType for glyph pre-rendering and basic glyph
geometry and HarfBuzz for text layouting (i.e. ligatures, kerning, ...).
Currently all used glyphs must be prerendered into texture atlas, other
glyphs are simply not rendered (although the layouting code handles them
like if they are there).
Text rendering supports UTF-8, although glyph pre-rendering is currently
ASCII only, as I couldn't find any working implementation of Unicode
STL function in recent GCC versions. Will be fixed later.
* CMAKE_SHARED_LIBRARY_CXX_FLAGS is empty here, caused CMake errors.
* CMake's OBJECT target has a bug that it doesn't define target_EXPORTS
as with other library targets, so it's needed to define it manually.
It also fixes empty flags issue.
* Visibility headers weren't updated for OBJECT targets, they now also
catch *Objects_EXPORTS defines.
Reusing macros MAGNUM_EXPORT and friends already used for Windows
builds. For exported classes added MAGNUM_LOCAL to private members which
are not referenced from any inline function. Added explicit
MAGNUM_EXPORT to private members which are referenced. CMake provides
its own macro <target>_EXPORTS, using that instead of
set_target_properties().