Improved implementation for regenerating translation path points

Optimised translation motion path regeneration by not recreating points
for computation. Bench mark timings improved from 4-5ms to 0-1ms for
that specific block of codes.

removed rotation path generation for the time being
Bug fixes related to object views

Fixed bug where interpolating without an active key causes a crash
Fixed bug where Rotation motion paths are not enabled
Fixed bug where motion paths of keys with 0 duration are drawn
Fixed bug where translation paths are not drawn at the correct place
Fixed bug where interpolation ghost appears at the previous frame boundary when interpolating at the end of a reference frame timeline.