...and unify region overlay and snap-to-edge overlay into overlay.c.
Snap-to-edge overlay is delayed for 500ms to prevent flickering when
the view is dragged from an output to another (demo in discussion labwc#1613).
This also fixes a bug that region overlay is not shown when a modifier
key is re-pressed.
Made all header files to have LABWC_ prefix in include guard identifers.
Converted from __LABWC_ in 35 include/ files.
Converted from __LAB_ in 5 include/ files.
Added LABWC prefix to 3 include/ files.
Added include guards to 3 include/ files.
The double underscores were removed since according to C standard
those "are always reserved for any use".
When wanting to snap to a region when starting the move
operation with A-Left (or a similar mousebind which includes a
modifier), the modifier - or another one - must be pressed again.
Fixes#761
