fixed RM 7705, add run_multiple, add rex/parser/generic...

Adds Rex::Parser::GenericWithEscape at
lib/rex/parser/generic_with_escape.rb which is used via run_multiple
which was added to lib/rex/ui/text/dispatcher_shell.rb which parses for
multiple commands (separated by ';' and escaped by '\\' by default) and
then calls run_single.

Running multiple commands was egypt's desire, but I don't think we ever
created a ticket for it.

Most run_singles were converted to run_multiple except those running a
single command like run_single("quit") etc.

Tested with msfconsole -x, msfconsole -r, the resource command, and
sending multiple commands at the msfconsole command line.
Try:
msfconsole -x set VERBOSE true;show options; set VERBOSE false (or any
other combo, and the same with:)
msfconsole -r test.rc (where test.rc has commands similar to above)
resource test.rc
msf > set SMBUser admin;set SMBPass pass;exploit -j
etc