add version of tipremove that doesn't require graph compression
stop tipremove search if max length is surpassed
rename previousNodes to visitedNodes
fix bug where MIN_LENGTH_TO_KEEP isn't kept between iterations
make TipSearch consistent with other msgs: use Integer, not int for length
rename TIP_WITH_SEARCH to TIP; old version to TIP_SINGLE_NODE
Merge pull request #73 from uci-cbcl/wbiesing/implement-tip-remove-with-search

add version of tipremove that doesn't require graph compression