Make map_directory_child_fs() refuse the names "." and "..".  This is
currently the interface where an attacker may inject a manipulated
path (through the "update" command).

Added the function map_spl_utf8_to_fs() which replaces
utf8_to_fs_playlist_path().

g_error() is fatal by default.  Use g_warning() for non-fatal
initialization errors.

Due to an off-by-one bug in map_fs_to_utf8(), the function returned
database paths with a leading slash.

Clients which have authenticated via unix socket may add local files
to the MPD playlist, provided that they own the file.

Moved the musicDir variable and its initialization code from path.c to
mapper.c.

The mapper library maps directory and song objects to file system
paths.  With this central library, the code mixture in path.c should
be cleaned up, and we will be able to add neat features like aliasing.