"Professional CMake" book suggest the following:
"Targets should build successfully with or without compiler support for precompiled headers. It
should be considered an optimization, not a requirement. In particular, do not explicitly include a
precompile header (e.g. stdafx.h) in the source code, let CMake force-include an automatically
generated precompile header on the compiler command line instead. This is more portable across
the major compilers and is likely to be easier to maintain. It will also avoid warnings being
generated from certain code checking tools like iwyu (include what you use)."
Therefore, removed the "#include <PreCompiled.h>" from sources, also
there is no need for the "#ifdef _PreComp_" anymore
During the LinkMerge, a new icon
`Std_CoordinateSystem.svg` was used
for the `App::Origin` object that appears in
`PartDesign::Body`. However, this icon
doesn't look as good as the original `CoordinateSystem.svg`.
This commit renames the old icon to the new name. The newer icon
is kept as an alternate version `Std_CoordinateSystem_alt.svg`.
In addition, a new icon `Std_Placement.svg`
is provided for the `App::Placement` object, which previously
was also using `CoordinateSystem.svg`.
In this way, `App::Placement` and `App::Origin`
use different icons and there is no confusion
in the tree view.
* Add always zoom invariant and always on top rendering to
ViewProviderDatumCS
* Add a new utility class AxisOrigin for more efficient axis rendering.
Also exposed to python.
* Change ViewProviderPlacement to use AxisOrigin for rendering.
A single instance of AxisOrigin is shared by all
ViewProviderPlacement. Selection context is used to distinguish among
different instances.
