svnwrap: Refactor the svn_auth_ssl_server_trust_prompt to add other handler - Since there are five handler, change to SubversionPrompt class from svn_auth_ssl_server_trust_prompt(). - Moved out of the handler to check the callback function is non-None.

include Makefile hgsubversion/help/*.rst
recursive-include tests *.py *.sh *.svndump *.txt