Fix bug in PlanStepEx::toString crashing with AttackGroundAction

Signed-off-by: MHesham <mhesham.fcis@gmail.com>
Prepare engine for offline learning + Merge branch 'master' of https://github.com/RtsAiResearch/IStrategizer

Conflicts:
	Source/IStrategizer/PlanStepEx.cpp

Signed-off-by: MHesham <mhesham.fcis@gmail.com>