When building the connectivity database, we should not be using the
connectivity to check for shapes.
To make this deterministic, we introduce two flags (ALWAYS_FLASH and
NEVER_FLASH) that are used with connectivity building to determine
whether a pad is flashed for connectivity or not. ZONE <-> PAD/VIA
connectivity will be checked with ALWAYS_FLASHED and all other
connectivity will be checked with NEVER_FLASHED if they are marked for
potential annular ring removal. If they are not marked for removal,
they will be checked ALWAYS_FLASHED.
Fixes https://gitlab.com/kicad/code/kicad/issues/11114
Bitmaps are now identified by an enum class instead of by pointers.
Bitmap loading and caching is now handled by a class in common, and
we no longer compile most bitmaps into the binary, so there is no
longer a bitmaps static library.
Instead, bitmaps are archived to a .tar.gz file which is installed
in ${KICAD_DATA}/resources/images.tar.gz
The source PNGs are checked in to Git as the original CPP files were,
so that people can build without the required dependencies to convert
SVGs to PNGs.
Initial support is also added for dark theme icons, although this
is not yet exposed in the GUI.
Stubs are present for multi-resolution image resources, but this is
not fully-baked yet and could use some refinement.