plugins/shakecursor: Enable by default

Multi monitor setups with 4K screens are not uncommon and one of the annoyances associated with such setups is that you lose the track of the cursor sometimes. It's natural to shake the cursor in such occasions.

This change enables the shake cursor effect to improve the desktop experience. One potential risk associated with doing so is that the cursor can be magnified in some undesired situations. It is true. But we took a great precaution of that and added some heuristics to avoid triggering the effect in such cases given all the data we have available.

Draft:

• ShakeDetector needs some optimizations: !5364 (merged)