set up start of 0-size Operator arrow
redone dimension system working working

only tested for drawing number line so far.
dimension system tested for number line display
arrow dimensions work

still need to draw arrow head
double-arrow location working

still need to have dragging/clicking target implemented
basic functionality working

still need to finish drawing arrows properly
arrow heads draw

pushed out to method
visuals improved

arrow heads all showing where required. Horizontal lines to connect
adjacent operators.
Operator class tab/file deleted

no longer required
Merge pull request #1 from Cheddles/Operator-class

Operator class