revert Android.mk back after copying SDL_mixer and SDL_ttf

update the core/android/SDL_android.cpp fix some includes in Android.mks, use a different host to download some libs, sdl doesn't have up to date tarballs..

these are needed for ndk-build or it won't know what api to build it for

Added a script to simplify building the android port

some tweaks to the build process, cmake now generates some vital files, fpc only compiles those files which have been changed since the last time, SDL still does not work

remove the incorrect text that people need to download before playing