New session dialog fixups:

New session dialog fixups:
 - The name specified on the command line for the new
   session comes up in the dialog
 - The editor will not appear below the NSD at startup

Command line parameter fixups:
 - You can't specify both a new session and a old
   session to load at the same time.
 - Ardour will abort if command line parameters are
   incorrect

Declick faster. Fixes audible and annoying volume ramps
when running ardour at large buffer sizes.

Make it impossible to arm tracks which have un-connected
inputs.

git-svn-id: svn://localhost/ardour2/trunk@765 d708f5d6-7413-0410-9779-e7cbd77b26cf