Improve object rotation API in libgeda + gschem
Implements the o_rotate_world() function which rotates any object, and
o_{glist,list}_rotate_world() functions which rotate lists of objects.
Moves o_complex_rotate_world() from gschem into libgeda, and modifies
appropriate places in libgeda + gschem to use this new API. The gschem
function o_rotate_90_world() is greatly simplified, becoming a
convenience function calling o_glist_rotate_world() and ensuring all
necessary drawing and connection updates are made. This function is
renamed o_rotate_world_update().
Removes the o_{complex,text}_rotate_lowlevel() functions which are made
redundant with the above changes.