Added initial cmake implementation
Added hacky workaround so homebrew doesn't need to force link libxml2
and zlib
Fixed the readme to better reflect features in the build system
Updated CMakeLists with a few comments and .pc generation
Updated CMakeLists.txt to only include allegro_main for OSX and iOS
Merge pull request #4 from belak/cmake_migration

Moving build system from bare Makefile to CMake.