on the first MidiClock Message after the start Message
* removed debugging output from session_process.c
* fixed bug: calculate a more sensible speed value on transport start
* fixed typos in Slave docs
* refactored MidiClock_Slave for better readability
* made MidiClock_Slave react to continue messages
git-svn-id: svn://localhost/ardour2/branches/3.0@4365 d708f5d6-7413-0410-9779-e7cbd77b26cf