Adds handling of hexadecimal encoded character reference entity (Fixes GH#6).
Restrict to real ascii (0-127 not 0-255, 128-255 depends of encoding).

Bug discovered during tests of the fix for GH#6. All fixed now.
Extends regexp to match () and @ (GH#9 and GH#7)
Merge branch 'xakz-bad-charref'
Merge branch 'extends-regexp-matching' of https://github.com/xakz/urlscan into xakz-extends-regexp-matching
Merge branch 'xakz-extends-regexp-matching'
Updated README