[LinuxCNC/linuxcnc PR#279] axis: keyboard shortcuts for feed override and joint activation

currently there are inconsistencies in the way the keyboard shortcuts operate for the above

this patch causes the following operations:

if the joints radiobuttons are visible then 012345678 activate the corresponding joint

if the axes radiobuttons are visible then `1234567890 set feed override from 0% to 100% in 10% increments

Signed-off-by: Phillip Carter

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