Change some key bindings to make editing easier

It's difficult to use on laptops which often lack separated Insert and
Delete keys.
Add some more tools to Yadex's repertoire

 * 'w' key splits a sector in vertex mode
 * 'T' key transfers line properties (especially sectors)
 * 'Z' key changes the sector of an area (all surrounding linedefs)
   either to an existing sector or to a new one.
Add the fixbuild patch from AUR
yadex.cfg: change the default search path

Many packages for distributions look for game data to be placed in
/usr/share/games/doom
Apply the make patch from AUR

Fixes the configure script and GNUmakefile so it actually builds.