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.
The bundled copies of LibPNG and zlib have been updated to the versions
shipped with FLTK (as these were convenient to build), and I've put in new
static libraries compiled with Visual Studio 2003 .NET. These libraries
link cleanly even with Visual Studio 2013 Express, so they should work for
just about every version of MSVC out there that can compile SolveSpace.
The MSVC makefile is also now a little nicer, and the SpaceWare Input
library header #includes have been adjusted to drop the si/ prefix (for
consistency with how LibPNG/zlib are handled).
(in my case, a SpaceNavigator). I can transform the view of the
part, or transform a part in an assembly.
Also fix up mouse wheel input, so that it works even if it comes in
chunks of less than 120 units.
[git-p4: depot-paths = "//depot/solvespace/": change = 2019]
whitequark
Daniel Richard G
Jonathan Westhues