Removed debug output
Added tunnelling specs
Walkability takes into account clearance
setClearance renamed to evalClearance
evalClearance returns the amount of clearance
Fixed syntax error, as of commit c05fce9
Updated Grid module documentation
Updated isWakableAt documentation
Fixed failing specs on evalClearance return value
New implementation of evalClearance, safer than the previous
Added evalClearance context
Added clearance specs