Allow more control over the output of pri debug

This changes the debuglevel of 'pri set debug' to a bit mask allowing the user
to independently select bits of output:
1 libpri internals including state machine
2 Decoded Q.931 messages
4 Decoded Q.921 headers
8 raw hex dump of the full frames

Additionally, this ensures that the meaning of "on" does not change and
intrudces intense and hex to simplify usage.

(closes issue ASTERISK-17159)
Original-patch-by: wimpy


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@354165 65c4cc65-6c06-0410-ace0-fbb531ad65f3