handle breaking characters in card names+issues

+ has its own meaning of course, and / ~ and | are already disallowed

Latest testing is at http://sandbox.wagn.org/wagn/name_testing_3

Known problems to be ticketed separately or at least discussed

• allow right brackets in links
• allow creation via link with quote or percent
• leave underscore in cards created via link
• handle forward-slash properly
• handle HTML entity characters properly
• handle Unicode characters properly