multiple regexes cannot have identically named capture groups

[ComaVN]

When more than one regex/url pair is used, named capture groups cannot have the same name.

in trac.ini:

[regexlink]
regex1 = \bexampleA(?P<exampleid>\d+)\b
url1 = http://example.org/A\g<exampleid>
regex2 = \bexampleB(?P<exampleid>\d+)\b
url2 = http://example.org/B\g<exampleid>

result: error: redefinition of group name u'exampleid' as group 35; was group 33

Furthermore, names of capture groups could collide with named capture groups of other WikiSyntaxProvider plugins.

Names should be automatically prefixed with "regexlink_1_", "regexlink_2_", etc. in the regex and the replacement url.