add another test for the invalidate of the graphmanager
add another test for the invalidate of the graphmanager

this one tests to determine whether the graphmanager is invalidated when
a vertex is added

Signed-off-by: Sam Phippen <e5a09176608998a68778e11d5021c871e8fae93c@googlemail.com>

samphippen/spe,samphippen/spe,samphippen/spe,samphippen/spe