urlstring testing/enhancement (copy)

[Chad Yates]

I just started recieving list messages again today.  It appears that my
previous messages were lost, so I'm forwarding them again...

I built urlstring testcases this weekend. Here are the test cases performed:
  URLStringTest.testBinaryBase64EncodeDecode ...
  URLStringTest.testStringVersion ...
  URLStringTest.testTypicalUrlEncodeDecode ...
  URLStringTest.testTypicalTextBase64EncodeDecode ...
  URLStringTest.testSimpleTextBase64EncodeDecode ...
  URLStringTest.testComplexTextBase64EncodeDecode ...
  URLStringTest.testPaddingPerfect ...
  URLStringTest.testPadding1Short ...
  URLStringTest.testPadding2Short ...

I have some issues to resolve with the b64Decode function, as it appears to
not work correctly when the base 64 output is padded to a multiple of 3.  I
have patched my version, but wonder if it is just a problem on my system.
I'll upload some test code if someone is willing to try it.

I also added Base64 functions that take std::string arguments for the encode
output and the decode input.  I don't know where the line is supposed to be
relating to std::string usage as I see most of common c++ is char* based,
but there seems to be std::string usage in some classes.  personally I like
having it as an overloaded version.  I can post diffs showing the new
functions if they are wanted.

,Chad