include default github .gitignore content
Added nav specific build directories.
dwa_planner: fixed bug where robot failed to turn at start of plan.
The logic in question was lost in the groovy refactor.
dwa_local_planner: removed PreferForwardCostFunction to encourage turn-in-place at start of plan execution.
PreferForwardCostFunction was introduced in groovy.
costmap_2d: Added 'inf_is_valid' option for laserscan observations.
costmap_2d: footprint_padding param was ignored, now using.