axis: get list of configurable colors and their defaults from glcanon
axis: get list of configurable colors and their defaults from glcanon

before this, adding a new color required changes in axis.py, options.py,
and glcanon.py.  now, only changes in glcanon.py will be needed.

cdsteinkuehler/MachineKit,ArcEye/MK-Qt5,RunningLight/machinekit,ianmcmahon/linuxcnc-mirror,unseenlaser/machinekit,ArcEye/machinekit-testing,cdsteinkuehler/MachineKit,bmwiedemann/linuxcnc-mirror,mhaberler/machinekit,aschiffler/linuxcnc,ArcEye/MK-Qt5,narogon/linuxcnc,araisrobo/machinekit,cdsteinkuehler/MachineKit,unseenlaser/machinekit,araisrobo/linuxcnc,cnc-club/linuxcnc,RunningLight/machinekit,cnc-club/linuxcnc,ianmcmahon/linuxcnc-mirror,cnc-club/linuxcnc,ArcEye/MK-Qt5,araisrobo/machinekit,araisrobo/machinekit,EqAfrica/machinekit,ArcEye/MK-Qt5,Cid427/machinekit,kinsamanka/machinekit,bobvanderlinden/machinekit,araisrobo/machinekit,EqAfrica/machinekit,ArcEye/machinekit-testing,bmwiedemann/linuxcnc-mirror,araisrobo/linuxcnc,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/linuxcnc,mhaberler/machinekit,strahlex/machinekit,EqAfrica/machinekit,ianmcmahon/linuxcnc-mirror,Cid427/machinekit,unseenlaser/machinekit,RunningLight/machinekit,ArcEye/machinekit-testing,EqAfrica/machinekit,kinsamanka/machinekit,cdsteinkuehler/linuxcnc,narogon/linuxcnc,aschiffler/linuxcnc,ianmcmahon/linuxcnc-mirror,bobvanderlinden/machinekit,mhaberler/machinekit,bobvanderlinden/machinekit,bmwiedemann/linuxcnc-mirror,araisrobo/machinekit,bobvanderlinden/machinekit,ArcEye/machinekit-testing,mhaberler/machinekit,narogon/linuxcnc,narogon/linuxcnc,ikcalB/linuxcnc-mirror,ArcEye/MK-Qt5,cdsteinkuehler/linuxcnc,Cid427/machinekit,kinsamanka/machinekit,strahlex/machinekit,araisrobo/machinekit,kinsamanka/machinekit,RunningLight/machinekit,cnc-club/linuxcnc,cdsteinkuehler/MachineKit,strahlex/machinekit,Cid427/machinekit,bobvanderlinden/machinekit,RunningLight/machinekit,unseenlaser/linuxcnc,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,Cid427/machinekit,unseenlaser/linuxcnc,ikcalB/linuxcnc-mirror,bobvanderlinden/machinekit,kinsamanka/machinekit,ArcEye/machinekit-testing,unseenlaser/machinekit,cdsteinkuehler/linuxcnc,narogon/linuxcnc,bobvanderlinden/machinekit,strahlex/machinekit,strahlex/machinekit,Cid427/machinekit,ikcalB/linuxcnc-mirror,RunningLight/machinekit,aschiffler/linuxcnc,EqAfrica/machinekit,mhaberler/machinekit,ianmcmahon/linuxcnc-mirror,unseenlaser/machinekit,unseenlaser/linuxcnc,mhaberler/machinekit,cdsteinkuehler/linuxcnc,mhaberler/machinekit,araisrobo/machinekit,bmwiedemann/linuxcnc-mirror,kinsamanka/machinekit,ArcEye/machinekit-testing,EqAfrica/machinekit,ikcalB/linuxcnc-mirror,araisrobo/machinekit,EqAfrica/machinekit,araisrobo/linuxcnc,Cid427/machinekit,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/MachineKit,RunningLight/machinekit,ArcEye/machinekit-testing,unseenlaser/machinekit,ArcEye/MK-Qt5,bmwiedemann/linuxcnc-mirror,unseenlaser/machinekit,strahlex/machinekit,araisrobo/machinekit,strahlex/machinekit,ArcEye/MK-Qt5,bobvanderlinden/machinekit,cnc-club/linuxcnc,bmwiedemann/linuxcnc-mirror,RunningLight/machinekit,cdsteinkuehler/linuxcnc,ArcEye/MK-Qt5,aschiffler/linuxcnc,cnc-club/linuxcnc,unseenlaser/linuxcnc,araisrobo/linuxcnc,Cid427/machinekit,ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,kinsamanka/machinekit,kinsamanka/machinekit,araisrobo/linuxcnc,cnc-club/linuxcnc,unseenlaser/machinekit,aschiffler/linuxcnc,EqAfrica/machinekit,unseenlaser/linuxcnc,ArcEye/machinekit-testing,cdsteinkuehler/MachineKit,mhaberler/machinekit