Merge pull request #319 from wolfmanjm/upstreamedge

Add M203 to change max feedrates on the fly. Saveable with M500. Also wait for queue empty before changing accleration with M204
change minute -> second in relevant comments
Arm solutions: use appropriate constants
Parsing of relative path corrected

absolute_from_reletive() now returns an absolute path that accounts for
../ and ..  in relative paths
Removed incorrect addition of trailing / from folder in cd_command()
Merge pull request #320 from gkbeer/edge

Parsing of relative path corrected
extend gkbeears fix for cd to player.cpp