Added option for the min required hand distance to start arm-swing locomotion

Thank you, community, for your feedback - we have learned that the min intra-hand distance required to initiate arm-swing locomotion may have made it hard to use arm-swing and have made change accordingly.

• A new config option, "min hand distance" is now available in the UI. Defaulting to 0.125, it now allows easier initiation of arm-swing locomotion.