[FEATURE REQUEST] Pets Thorns damage + Average Thorns damage

## Observation

Thorns damage can be computed, or at least approximated (which is a great insight).
See the formula from Sanguinary Vambraces (_Thorns damage_ = _Thorns value_ x _all bonuses_)

But... currently, you do not get insights on how much your pets can deliver Thorns damage, given optimizations you apply on Skeletons, Mages, Golem. For example, you can optimize pets Thorns by applying the passive skill Aberrant Animator, the Singularity rune offered by Razeth's Volition, the number of pets, etc.). These optimizations should be computed and shown somehow.

## Proposal
1) Under each pet skill, in addition to damage, add a line : Thorns damage
2) In global stats on the right, add a line : Average Thorns damage (Pets + you + Sanguinary Vambraces)