Timestamps in V0r4 should allow graph to animate and single step

[adrianco]

See https://github.com/adrianco/spigo/blob/master/json/lamp.json for example

Timestamps may not be written to the file in order, so first sort the input file by timestamp.

Provide options to load the whole thing in one go ignoring timestamps, forget and done entries (current default), load one step at a time with a next and back button, or loop the file in slow motion with a speed control option.