#1793 Some Perl 5.22 updates for LexPerl

[Kein-Hong Man]

This update adds support for Perl 5.22 to LexPerl:
(a) Double-diamond operator <<>>
(b) Hexadecimal floating point literals
(c) Repetition in list assignment
Items (a) and (b) fixes the most obvious breakages in highlighting. There is still some new syntax that LexPerl does not support, such as the subroutine prototype syntax interacting with subroutine attributes (from Perl 5.20) but the highlighting breakage is not too bad and will be dealt with in the future.
Attached is LexPerl.cxx and test samples for Perl 5.22.

[Neil Hodgson]

Committed as [0dbc4b].

The commit also includes the test case file and some changes to the lexing test code to allow use of that file.