Added error for no selected client library.
Forced resizable to true for fullscreen windows.
Shortened window struct member.
Formatted public header, removed per-token docs.

Some tokens are used for more than one purpose, making it difficult to write
good documentation on the token itself.  These tokens should instead be
described in the documentation for each function or callback that uses them.
Moved WM_DELETE_WINDOW retrieval to init.
Renamed WM atom struct members for clarity.
Moved to WM_STATE for iconify events.
Added X error text to context creation failure.
Fixed leak of wide string window title.
Renamed chdir option, added OS X menu bar option.

Some command-line programs want to render to hidden windows without any
visible UI.  This option makes this possible on OS X.