toolbar support.
Make toolbar support a separate .dll

This way if toolbar.dll isn't instaled the plugin still works
move debug stuff in RCSBuildAid.cs to Debug.cs
this is no longer used.
'cause i don't want to log flooded even in this very unlikely case.
Merge branch 'master' into toolbar

Conflicts:
	RCSBuildAid.cs
slight improvement getting the resource mass for dV calc
change button icon when enabling the plugin.
better handling of the CoM render and active status when using the toolbar.
Merge branch 'toolbar'
save direction setting
hide dV readout when the value can't be trusted, like with modded RCS.