It was never really needed, since both Linux and OS X, where
GlOffscreen is used, guarantee that the API we need is present,
on all OS versions we're interested in.
Also, reorganize GlOffscreen consistently with the rest of our
codebase, and don't use RAII for OpenGL resource management because
of its requirement for an active context.
We now build and distribute Windows executables for every release,
so mention that. Conversely, the Debian packages are basically
unusable, so drop them for now.
We are going to use freetype instead of the old custom TTF parser,
since the old parser has many annoying bugs when handling non-Latin
fonts and fixing it is not really worth the time.
On Windows, Freetype is built from a submodule.
On Linux and OS X, Freetype is provided together with the desktop,
though development files have to be installed separately.
I do not update it anymore and it's probably not the best solution
for distributing SolveSpace on Linux. In the meantime, the builds
from GitHub releases should be convenient enough.
As a side effect, zlib and libpng are now git submodules,
based on their respective official git repositories.
This is necessary, because MinGW has a different ABI and
it cannot use the prebuilt binaries built by MSVC.
The submodules are also used for Windows, for several reasons:
* to allow 64-bit builds;
* to allow using newer MSVC, which doesn't like the prebuilt
libraries;
* to keep the libraries updated.
whitequark
ruevs