Removed unnecessary touchZoomDistance resets

The `_touchZoomDistanceStart` and `_touchZoomDistanceEnd` resets are not needed since the values will be set in the `touchstart` function when two or more touches are present.

Fix bower.json ignores

Multitouch fixes

* Removed unnecessary `default` case for two or more touches on `touchend` to prevent issues with 3 or more touches.
* Reset zoom distances on `case 0` and `case 1`. I couldn't combine them easily without doing a separate `if` statement.
* Simplified `case 1` action to set `_moveCurr` and `_movePrev` to the current touch position preventing camera jumping next time `touchmove` is called.

Related to issue #7185 and pull request #7406

Blender export bugfixes

Add support for loading SkinnedMeshes from SceneLoader + bug fix.

Multitouch fix for TrackballControls

Renaming of commands (aesthetics)

Added "var " before function expressions

Fix for #7185. After using two fingers, the camera would rapidly rotate if both fingers were not removed simultaneously. Adding in some state checks in `touchmove` and `touchend` prevents the jump from the null `_movePrev`, allowing users to quickly go from zooming and panning to rotating.

adjustments to the documentation according to naming convention. Old: "Cmd[..].js" new: "[..]Command.js"

Implementation of Undo/Redo functionality for threejs-editor