pointers-changed: Adding the pointers changed function

Also added a cursor layer above all others.
Pointers Changed: Responding to Code Review

Added documentation for window.insert-cursor
Make the pointers-changed function more functional.
Pointers Changed: Fixing typo from rebase

Forgot to include the end square bracket from the rebase.
Added fancy wires

and a small bugfix on setting the wire styles
Changed updating behaviour

Now set-start and set-end can be called in any order, and used to move
wires around. (like before but I broke it)
Added richer pointer information from leap

Added a helper class PointInfo which is used for sending information to
the window via pointers-changed method.

Altered the leap cursor to send the new data type.

Preliminary changes to window.ls to show off the new features.
Pointer Styling now in view_style

Added pointer styles to view_style, as well as a method for converting
PointInfo -> paper.Shape so they can be displayed.

Also tweaked leap_cursor to help avoid detection of 'spurious' fingers
when panning.
Fixed conflicts