[vile] tcl syntax filter

[Wayne Cuddy]

Not sure if this is an easy fix or not as I've not looked at the code
but the TCL syntax highlighter does not seem to recognize the line
continuation character (\) while processing string literals, it
terminates at the end of the line.

The following works:

set mystring "this is my string"

However in the next fragment '"this is line1\' is highlighted correctly
but 'this is line2' is not, and '" ;# comment' is highlighted
as a string literal.

set mystring "this is line1\
    this is line2" ;# my comment

Wayne