Implement getters/setters

I would like to have getters/setters all across the code.

This would allow to access (and modify) all those things that now have a getWhatever() and setWhatever method, like L.Map.getZoom() and L.Map.setZoom()

e.g. instead of:

map.setZoom(map.getZoom() + 1);

one could do:

map.zoom++; 

I guess some of the code would become much more simpler. The main downside is that getters/setters are part of the ECMAscript 5 standard, so IE8 is out. Other downside is that it seems that the only way to copy getters/setters from an L.Class.extend(mixin) definition is to resort to the method described in #3464, which might affect performance.

[mourner]

I’m not a fan of getters/setters, having used them in GL JS. They do all the work that’s happening under the hood implicitly, which often makes it much harder to debug. Lacking IE8 support is also a blocker for now.

[jonkoops]

Adding this to the v2 milestone, and since this would be a breaking change I will mark it as such.