Adding some tests on component counts with imports.
Adding some tests on component counts with imports.

Need to confirm the behaviour of the componentCount() method and make
sure we know what to expect. Initial tests on imported components to
set the current status of the implementation, which disagrees with the
documentation.

hsorby/libcellml,nickerso/libcellml,hsorby/libcellml,libcellml/buildbot-testing,MichaelClerx/libcellml,nickerso/libcellml,cellml/libcellml,cellml/libcellml,hsorby/libcellml,nickerso/libcellml,MichaelClerx/libcellml,cellml/libcellml,libcellml/buildbot-testing,cellml/libcellml,nickerso/libcellml,hsorby/libcellml,MichaelClerx/libcellml