mapindex update

Fixed a mapindex_name2id problem that'd persistently not fix a broken mapindex data (e.g. char save/last map data being incorrect). It'll now align it to MAP_DEFAULT when such error occurs.
Also speeded up mapindex_name2id queries, replaced the loop by the red-black-tree db lookup.
Special Thanks to yommy~!

Signed-off-by: shennetsind <ind@henn.et>