Then you can just toggle back and forth with '/'.
One day, these frames should use a tool manager for this
kind of thing (also for the ruler tool, but lots of other
things on top), but for now just bind a char hook.
There was a gentle mish-mash of booleans, some with
true being left/right and some up/down, and some functions that
can flip in both axes (which is never actually done, and doesn't
really make geometric sense).
Replace all this with the FLIP_DIRECTION enum class, which makes
the intention completely unambiguous.
This also then allows a small scattering of simplifications,
because everything takes the same type and you don't have to
fiddle booleans to fit.
(It's still leaking into BOARD_COMMIT and some other places, but at
least it no longer leaks into all the edit tools.)
Also fixes some bugs when moving/copying/pasting multiple selections
containing length-tuning patterns.
Moves forced-transparency setting down into VIEW_ITEM so that it can
be used to place forced-transparent objects in a different target.
This keeps EnableDepthTest() from equalizing the alpha values between
the two symbols (or two footprints).
