Improved efficiency of ODE45
	modified:   copasi/trajectory/CExpRKMethod.cpp
	modified:   copasi/trajectory/CHybridMethodODE45.cpp
Not successful modification. More need to do for slow reactions
	modified:   CMakeLists.txt
	modified:   copasi/trajectory/CHybridMethodODE45.cpp
	modified:   copasi/trajectory/CHybridMethodODE45.h
Fixed bug about slow reactions
	modified:   copasi/trajectory/CHybridMethodODE45.cpp
Improved efficiency of ODE solver on function of interpolation(). Declared some simple functions as inline.
	modified:   copasi/trajectory/CExpRKMethod.cpp
- disable forced build of tests if they are not present in the source tree to allow compilations
- fix for bug 2083: use the creation data as modification date if none given, add warnings when model history is not complete, so that it can be displayed after export.
- fix for bug 2082: the issue was caused by a change in CQComboDelegate, that now also commits the data automatically when selected. This caused references / relationships to be created twice. I now introduced an argument to the combo delegate, that determines whether a commit happens or not.