Moved to timer based update, also handling keys more robustly.  Need to have non-arrow keys for movement also but not working yet.
Now keys are working- the keyCodes are always uppercase?  And not animating cat when not walking.
Now only putting one level on the stage, need to make a method for switching to other levels.
Have new set of masked regions where the intention is if the player steps into them they will be transported to the level specified in themap.json
Now am loading the exits pngs, though chrome seems to cache the json instead of reloading it after I change it.  Next need to actually inspect the pixel values in the mask and switch levels when proper.