* rulesets/mason/define_world.py: Use know() for prices rather
than the special case code.
* rulesets/basic/editor.py, rulesets/basic/mind/NPCMind.py:
Remove obsolete special case code for handling knowledge of
prices. Improve code to express distance to a location so
it neglects the vertical distance, and better handles the
very close case.
* rulesets/basic/mind/goals/humanoid/mason.py: Track the character
being helped in the help goal, and turn to face them when speaking.
* rulesets/basic/mind/panlingua/interlinguish.py: Add more support
for pronouns, conjugations and whitespace in regex used to match
certain sentence structures.
