added topic based clearning of obstacles
removed some commented out stuff
added initialization of utimes when a topic is added
removed last_utime cache creation for the non rolling window version - added checking
removed some output
removed some unneccasary output
fixed some bugs and added height map for the topics
added checking other layers at the same height for timeout - need to test
moved the implementation to the voxel_layer.cpp file
updated
renamed and added comments
changed printf to ros info/debug
added option to enable height checking - turned off by default
fixed bug that was only clearing obstacles that timed out at the same height
resolved conflict
fixed some commenting issues and indentation
added continue and fixed wrong print output
fixed typo
updated the comments
Merge pull request #18 from bosch-ros-pkg/global_layer_timeout_topic_with_height

Global layer timeout topic with height