add layout provider to manage level sets
add options menus

options menu
- game and video options
- language

video options menu
- switch fullscreen/windowed
- switch vertical sync

game options menu
- choose level set
- shuffle level order
- chosse game speed (slow/fast)
make ghosts less predictable with rogue strategy

fix a star algorithm to consider teleports
add open greedy levels 2 to 5
add MacOS support

- add platform specific headers and code
- OpenGL headers
- crash pad and stack trace (Linux/MacOS)
- priority boost (Win32)
- detect platform automatically; pass as PLATFORM macro
- fix BUILD and VERSION macros
- disable vsync by default on Linux
- start windowed
- add environment info:
	- name: user name
	- rw_dir: opengreedy directory in user home dir
	- ro_dir: formerly data_path
release v0.2