This is done by adding a stream interface to the PLUGIN class,
so that the test program can read in from stdin, as well
as the existing filename interface.
This makes the plugin interfaces a bit more flexible in general, as
they no longer require a file on disk to be present, they can
be used from memory too.
It also retains a manual implementation of the kicad_mod
parser, as the footprint access is a bit harder to provide a
streaming access to.
Kicad, Windows specific: disable a overzealous wxWidgets assert when reading a file.
When reading (and writing) a file, we must switch the current locale to "C" for LC_NUMERIC.
Unfortunately, on Windows, a wxWidgets assert was shown when reading some items (bitmaps images).
This wxWidgets assert (related to decimal separator) is overzealous and is now hidden only when reading/writing files.
CanonicalizeName only adds the lib prefix and .so suffix, so loading
libngspice.so fails until the development package is installed.
MAC/Windows code paths lookup soversion 0 of ngspice as well, as this
is the only compatible version.
It is possible for an async thread to simply be deferred if not
specifically set to async. In which case, until the return value is
requested, the loop may simply wait.
Threading: Moving connectivity search to std::async
By decoupling from std::thread, we can avoid the wait/sleep cycle in
checking the std::atomic completion variable. The std::future variables
are immediately returning without the additional atomic check cycle.
