Poke contribs to get Win32 building again.

Yay.
Adjust main Makefile to allow automating Android builds.

Assuming you have the Android SDK and NDK in PATH, use:
make ANDROID=y TILES=y android

It's far from flawless right now, but it's a decent start and it gets
the data files into a place where they will be usable from the Android
build once we write the code to hook it up.

TODO:
  - export the cflags from here for use within the Android project files
    so that they're not hard-coded; finding a way to do that with the
    source files would be good too (but seeing as we already have several
    hard-coded lists of source files that one's not as critical);
  - allow easy toggling between debug and release Android builds.
Remove a couple of files from the old Android build.

People might get confused as to why these are here, since they have
nothing to do with the SDL2 Android build.
try restoring the BUILD_ALL targets
Allow loading files from Android assets.

There are some diagonstics and tweaks here to get everything in a place
to be loaded in such a fashion.

The upshot of this is that SDL2 Crawl can now run on Android! This calls
for streamers and confetti.
Handle SDL_TEXTINPUT so that we can use Android's screen keyboard.

TODO on this front: resize the video around the keyboard if necessary.
Temporarily don't use SDL_TEXTINPUT on non-Android.

It's causing double keys; ideally we'd only parse _KEYDOWN for modifiers
so that we can have the best of both worlds.
Handle SDL2 window resizing; allow window to be resized.
Android: Don't quit when toggling visibility of soft keyboard.

TODO: get it to return when toggling it on.

One of these lines does nothing yet, but I suspect it will help with
resizing the display on keyboard toggle.