- Refactored the common part of cursor key movement and crosshair update
in the various GeneralControl
- Add x10 movement with the keyboard (CTRL modifier)
- Avoid fixup of the cursor position by dummy mouse movements generated
by cursor warping (original analysis and idea Chris Gibson)
- Do key handling in a way to permit sub-pixel cursor movement
*) add hotkey for setting the grid origin as 'S', in board editor, module editor.
*) re-position the function interface for cursor movement from BASE_SCREEN into
class EDA_DRAW_FRAME. This is a prelude to getting rid of BASE_SCREEN or
splitting it up.