Identifier Tracking

[LinqLover]

Concerns hpi-swa-lab/squeak-tracedebugger#74

Usage:

• TrackingSimulator debug: [
  	| x y |
  	x := Morph new.
  	y := x].
  BasicInspector openOn: y.

• in the context of a complex morph:

  TrackingSimulator debug: [
  	self allMorphsDo: [:x | x color]]

Next steps:

• Revise tracking and untracking places - currently, receiver et al. are not tracked properly
• Discuss need for transparent proxy
• Proper support for primitives
• Tests

Further work (can go into separate PRs):

• Discuss API for displaying tracked information and usage in production (for TDB, this approach would be slow)
• We could also use this to explain side effects from a sandbox or TDB retracing
• Discuss target package and category