The tests are now sorted by command type. This allows for more consistent
test creation as tests can be done per source code file instead of per
object type.
Added helper functions for common testing operations. The two main ones
are doCommand, which executes a MaxCtrl command and returns a result, and
verifyCommand, that executes a command and verifies the result via the
REST API.
Making the core a module proved to bring more problems than it solved. For
the sake of simplicity in installation and code coverage reporting, the
core is now completely contained in the `lib/` directory.
Also added preliminary coverage reporting with nyc.
