add commands to insert combining accents
add commands to insert combining accents

* add meta commands to insert combining accent code points:
  - M-`  insert-grave-accent
  - M-'  insert-acute-accent
  - M-^  insert-circumflex-accent
  - M-"  insert-diaeresis
* reordered some commands in qeconfig.h

dmacvicar/qemacs,dmacvicar/qemacs,dmacvicar/qemacs,dmacvicar/qemacs