SDL version of Cataclysm (still ASCII-only)

The forum user utunnels was kind enough to get us started on SDL-based tiles, by partially rewriting catacurse. The tiles version is still messy, but the ASCII version could be worth merging in (if only as a way to let Linux devs actually fix the I/O code used by some Windows versions).

Standard compilation, existing cross-compilation from Linux to Windows, and SDL compilation under Linux all work.

I seem to not have suitable headers for cross-compiling the SDL version, and it's rather inconvenient for me to compile directly in Windows (note that the Codeblocks/MSVC project files have *not* been updated, because I'm not sure which version should be the default).