src: Refactor ibuscomposetable.c
src: Refactor ibuscomposetable.c

Save raw integers of Unicode instead of code strings.
Use g_warning() instead of g_set_error().

BUG=https://bugzilla.gnome.org/show_bug.cgi?id=721120
R=Shawn.P.Huang@gmail.com

Review URL: https://codereview.appspot.com/282390044

fujiwarat/ibus,fujiwarat/ibus,ibus/ibus,ibus/ibus,ibus/ibus,fujiwarat/ibus,Keruspe/ibus,fujiwarat/ibus,Keruspe/ibus,Keruspe/ibus,Keruspe/ibus,ibus/ibus