PropListener - add a callback to property value get/set event

This is an enhancement of Matlab's hidden and unsupported addlistener function (within the uitools folder). It attaches a listener callback to one or more property (or properties) get or set event(s).

Acceptable events are PreGet, PreSet, PostGet and PostSet, which are triggered immediately before/after a get/set event on a handle property value.

Example:
proplistener(gcf,{'Visible','NumberTitle'},{'PreGet','postSet'},@myFunc)

See more extensive help section within.

Note: relies on undocumented and unsupported Matlab functionality. Use at your own risk. Comments welcome