ConvoEngine: Make max channel counts configurable.
IPlug: Update tooltips after (un)hiding controls.

You should call GetGUI()->UpdateTooltips() after (un)hiding controls, so on
Mac OS X Cocoa the tooltip rectangles can be recreated.

Conflicts:
	WDL/IPlug/IGraphics.h
	WDL/IPlug/IGraphicsMac.h
	WDL/IPlug/IGraphicsMac.mm
	WDL/IPlug/IGraphicsWin.h
[IPLUG] #ifdef COCOA_TEXTENTRY_BORDERED

define COCOA_TEXTENTRY_BORDERED if you want a blue rimmed text entry on cocoa guis