Initial class description for axis angle adjuster

taken from wheel class from fraction visualiser
select button drawn

button to select angle change drawn
bugfix (location)

location of vectors now correctly specified with origin in the middle of
the screen and the vertical axis oriented up=positive)

Vector location shown for current vector as debugging measure.
select and deselect working

no rotation yet
Draggable angle change working

working with all vector components visible during drag. OK and cancel
buttons showing but not functional
smooth dragging with angle displayed in degrees

Angle actually jumps to nearest degree for calculation and arrow display
purposes.

no arc arrow yet
component vector colours fixed

Colours now set as global variables and reflected in rotation tool.
round arrow working

used only on axis adjustment for now
bug fix

bearins calculations and arrow display fixed
Merge pull request #1 from Cheddles/AxesAngle

Axes angle