Fixed graph bug when blue was at 100%
Fixed link errors in com.h
View models can now have child view models.

A lot of reorganising involved. IUntypedObservable is now treated as a
first class citizen internally. This wasto sort out some dependency
issues. UntypedObservales can now be asked to cast their wrapped value to
a view model reference, which will throw bad_cast if it isn't a child view
model.
GCC doesn't support brace initialisation for references.