Simulate the character highlight search of VIM.

When end with search, highlight doesn't disappear(binding to F3).
If want to cancel all character search highlight, you can hit F4.
Because of above, that's F3 and F4, rebind "goto-line" to F2.
Repair that 'defvar-local' is void.

Under 24, emacs doesn't define defvar-local. So this configuration define
the system 'defvar-local' if the version of emacs under 24.