Lots of Things

Moved LineRenderers to separate object list.
Added option to view all current links.
Added visual distinction to active link.
Holding down LeftControl while creating a link will create the link in a new group.
Changed "Add" buttons to "New."
"New" buttons and LeftControl check for empty actives before making a new one.
Error checking for placing obstacles and changing tiles.

Removes speed increase from diagonal movement.