This mechanism sets up CMake variables that allow a user to select which
modules/libraries to create. Dependencies will be tracked down to ensure
that all of a module's dependencies are also enabled.
The modules are also arranged into groups.
Groups allow you to set the enable flag for a group of modules at once.
Thus, if you have several modules that are likely to be used together,
you can create a group for them.
This can be handy in converting user-friendly CMake options (such as
`VTKm_ENABLE_RENDERING`) to the modules that enable that by pointing to
the appropriate group.
When both examples and tests are on, there are a few tests created that
will install VTK-m and build the example against the install to make
sure that all expected components are installed. Since it requires the
full compile of a VTK-m application (and some VTK-m applications can
take a while to compile), increase the timeout for these tests.
The timeout is currently set to 10 minutes (600 seconds).
We now have a couple of the examples also being built against
the installed version of VTK-m as a test. This allow us to verify
that VTK-m installs and can be found properly.