Improve some of the breve/caron/cedilla mappings

* lisp/leim/quail/latin-pre.el ("latin-prefix"): Describe new 'c with
cedilla mapping'.  Extend caron description.  Correct dot above
description.  Add new mappings for 'a with breve' and 'c with caron'.
Add additional mapping for 'c with cedilla'.  Delete ~o mapping for 'g
with dot above'.
1 job for master in 46 minutes and 39 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #544
test-all

00:46:39