Mworks MWorks Core Components

More reworking of dynamic stimuli

• Eliminated the previously-added "finalize" pass for actions. Stimulus group references that depend on global variables cannot be fully resolved at parse time, so the dynamic stimulus actions must validate their target at execution time.
• Dynamic stimuli once again do not play by default. Instead, StandardDynamicStimulus now supports an "autoplay" parameter. A non-playing SDS subclass with autoplay set to true will automatically start playing the first time it draws (i.e. during the first stimulus display update after it's queued).
• Subclasses of DynamicStimulusDriver that need to perform additional actions when they start or stop should now override startPlaying() or stopPlaying(), respectively (being sure to call the base implementation from the override)
• Subclasses of StandardDynamicStimulus should once again implement drawFrame(). However, the function now takes only one argument (the StimulusDisplay pointer).
• Added some code to ensure that StimulusDisplay::getCurrentOutputTimeUS() always returns a valid time when the state system is running https://github.com/mworks-project/mw_core/commit/2d9c7ab84b7126d4d5...