Tile pattern Id can now be integers or strings.
Merge branch 'red-solarus' of https://git.gitorious.org/red-solarus/red-solarus into red-solarus
Remove useless string conversion function.

luaL_checkstring() already converts numbers to strings.
Add string tile ids to the ChangeLog.
Simplify the tile pattern parsing code.
Update the documention to string tile ids.
Quest editor: handle string tile ids internally.
Editor: show the tile pattern id when a pattern is selected.
Merge branch 'master' into string_tile_id

Conflicts:
	ChangeLog
Editor: implement renaming tile pattern ids (#559).

This is not finished: we need to automatically update existing maps when
changing a tile pattern id.
Editor: update existing maps when changing a tile pattern id.

Fix #559.
Indentation.