Provide Windows executables

[sikthehedgehog]

Windows people are accustomed to having prebuilt executables and also Windows doesn't come with a preinstalled toolchain (worse, makefiles aren't exactly portable), so I probably should start providing Windows executables for the tools.

Not too worried about Linux since GCC is nearly always preinstalled and you can just do make to build the tool :P

[RepellantMold]

SikMDTools_Windows.zip Well, not all of the tools are in here (namely mdtiler and echo2vgm) but I think it's good enough for now. (compiled these using VS2019's C compiler)

[sikthehedgehog]

That isn't so much the problem but making sure that executables will be available as soon as there's an update.

The sore point here is mdtiler, since it's the only one with external dependencies (libpng, which in turn depends on zlib). I need to stop being lazy and figure out again how to cross compile it (I'm using MinGW-w64 on Ubuntu), the big issue is that I want to make sure that I get a static library so mdtiler can be its own standalone EXE file, otherwise you have to carry around a DLL file with it all the time and it gets annoying.

I already have a cross compiler wrapper for the makefile here for all the other tools so those aren't an issue.