Added pseudocode-like comments for the main planner process.
Added interfaces for adding / checking variables binding histories to a state nodes
Added score calculation for selecting suitable rule for the current planning step
Added function: check if a rule is a resursive rule
Implemented Ground variables for a rule according to its forward state node
Added the framework for cost as heuristics inherited from the parents in one planning step.
Fixed some real-time inquery value for states for real time cost calculation
Merge pull request #165 from shujingke/shujing

Shujing