- fix for Bug 2051: allow a reaction interface to be temporarily invalid, as otherwise changes a user made will be lost.
- fix for Bug 2051: allow a reaction interface to be temporarily invalid, as otherwise changes a user made will be lost.

copasi/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,copasi/COPASI,copasi/COPASI,jonasfoe/COPASI,copasi/COPASI,copasi/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,jonasfoe/COPASI,copasi/COPASI,jonasfoe/COPASI,copasi/COPASI,copasi/COPASI,copasi/COPASI