- Changed IO's vector<Port*>'s to PortList

- Changed IO's vector<Port*>'s to PortList
- Added new Port classes, code to drive them
- Added PortList, which is a filthy mess ATM (nevermind that, it's the interface that's important at this stage)
- Added ChanCount, though it isn't very thoroughly used yet.  That's the next step....
- Fixed a few bugs relating to loading sessions saved with trunk
- Fixed a few random other bugs

Slowly working towards type agnosticism while keeping all the former code/logic intact is the name of the game here

Warning:  Removing ports is currently (intentionally) broken due solely to laziness.

git-svn-id: svn://localhost/ardour2/branches/midi@786 d708f5d6-7413-0410-9779-e7cbd77b26cf