"regexmatch" and "notregexmatch" can be used with anonymous %renames in the
same way as "match" and "notmatch" while "regextarget" specifies that the
argument of a non-anonymous %rename should be interpreted as a regular
expression.
Document the new functions.
Also add a new unit test for %regex also testing regexmatch &c and provide
test code for C# and Java verifying that it works as intended.
git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@12174 626c5289-ae23-0410-ae9c-e8d60b6d4f22