Syntax Highlighting: add support for Perl 5.10 and newer

The new Perl language syntax is not properly interpreted in SmartGit when showing diffs.

The wrong syntax colouring starts after the defined-or operator (//) introduced in Perl 5.10:

my $review = $model->test // !1;

This is equivalent to C logic:

Review *review = test() ?: nil;

SmartGit interprets it as a comment and colours everything after the '//' with green colour.