Add setting to turn off CompositionView drawing.

In the interests of performance testing, I need to isolate each part
of the system that is using CPU, and CompositionView is one of the
biggest users.  This is a setting that needs to be set manually
in the settings file, so it should have no effect on normal use
of rg.  Intended for debugging only.  Default is "1".  If set to 0,
CompositionView will no longer do any drawing.

See ~/.config/rosegardenmusic/Rosegarden.conf

[Performance_Testing]
CompositionView=1


git-svn-id: http://svn.code.sf.net/p/rosegarden/code/trunk/rosegarden@13253 cf6a83e7-f017-4305-b0b3-678bde24f230
Add setting to turn off transport MIDI in/out

This one doesn't use a lot of CPU on my machine.  About 4%.  It's
just enough to be annoying when doing performance measurements.

Also cleaned up the initializer list in TransportDialog's ctor.


git-svn-id: http://svn.code.sf.net/p/rosegarden/code/trunk/rosegarden@13254 cf6a83e7-f017-4305-b0b3-678bde24f230
Add setting for UI update interval.

For performance testing as with the previous two commits.

This will have an effect on the Windows port which I believe has the
update interval set to something other than 50.  That number has
moved up to the settings call as the default:

int updateUITime = settings.value("Update_UI_Time", 50).toInt();


git-svn-id: http://svn.code.sf.net/p/rosegarden/code/trunk/rosegarden@13255 cf6a83e7-f017-4305-b0b3-678bde24f230
Add update throttling to CompositionView

Some measurements from my Core i3-370M laptop while recording the first
20 bars or so of the third movement of the Moonlight Sonata...  
CompositionView was using about 38% CPU.  Now it's using about 12%.  This 
almost cuts total rg CPU usage in half from 57% down to 32%.

This also appears to close bug #1350, "Can't Record Beethoven".  I was
able to successfully record the entire 3rd movement of the Moonlight
Sonata on my machine after this change.


git-svn-id: http://svn.code.sf.net/p/rosegarden/code/trunk/rosegarden@13261 cf6a83e7-f017-4305-b0b3-678bde24f230