editor: Fix some offsets for multi-byte characters
editor: Fix some offsets for multi-byte characters

Signed-off-by: Jan Arne Petersen <8c3575d1e692bfe9fd3220cb3956503cdd270f15@openismus.com>

Gnurou/weston,Fantu/compositor-spice,Tarnyko/weston-xdg_surface_present,jonnylamb/weston,Tarnyko/weston-xdg_surface_present,krezovic/weston,Fantu/compositor-spice,giucam/weston,xorgy/weston,eyolfson/weston,kwm81/weston,giucam/weston,sir-murray/weston,Fantu/compositor-spice,udoprog/weston,mchalupa/weston,kwm81/weston,sir-murray/weston,udoprog/weston,jonnylamb/weston,krezovic/weston,mchalupa/weston,Gnurou/weston,eyolfson/weston,xorgy/weston