Make Gizmo rotation tool more ergonomic#712

Right now, the Gizmo rotation ball is quite clunky to use and trying to grab the thin lines to limit rotation to a single axis is hard and prone to failures, resulting in unwanted rotation that has to be reset by entering numbers. It is also hard to see whether you have grabbed the line or not especially with the green one, as the color difference is hard to judge at times, depending on the background it is used on.

I suggest to increase the thickness of the axis limiting lines, as well as their grab areas, in order to make it both easier to grab them and also make it easier to see if you have grabbed them.

Could be nice if Ctrl+Z puts back the last rotation if the rotation gizmo tool is selected

The hard to click nature also applies to the gizmo move tool.