handle M-e moving forward into a comment when looking at preceding
whitespace, and M-a moving backward into comment when looking at
following whitespace.
(c-comment-line-break-function): Don't break line in the middle of a string.
don't have the variable comment-line-break-function.
(c-electric-slash): Make this work as the final slash in a */ block
oriented comment closing token.
(c-comment-line-break-function): New function for proposed
mode-specific comment-line-break-function variable.
(c-electric-backspace): Must get 'supercede property
values to work with delsel and pending-del.
(c-electric-brace): Fix ebola eradication consequence
in the preserve-p test.