Fix memory leak when destroy component

[pmierkowski]

In file cytoscape-context-menus.js in line 122 there is added listener to document element: document.addEventListener('mouseup', onClick) but in the line 212 listener was removed from document.body element document.body.removeEventListener('mouseup', getScratchProp('hideOnNonCyClick')) which cause memory leaks in Angular 10.

[ksdev-pl]

Here's how it looks like before the fix:

Here's after:

It's a serious problem.

[canbax]

@pmierkowski Thank you this is a good catch. I suspect there are more memory leaks. After I call the destroy method of extension, all the event listeners should be removed. I see that still some event listeners are being called. If memory leaks are important for you, there are still memory leaks.

[pmierkowski]

@canbax Thank you for quick reaction. The above leak was the largest. I will watch them, if I find anything I fix it.