Importing moved into the primary scanner. Import statements now open up a new

Importing moved into the primary scanner. Import statements now open up a new
Scanner object which looks for outside code tokens that can be interpreted as
machine definitions, then sends them to the parser, all the while ignoring
everything else.

git-svn-id: http://svn.complang.org/ragel/trunk@144 052ea7fc-9027-0410-9066-f65837a77df0