MIKE 21 & MIKE 3 Hotfix 23-04-2010

This hotfix resolve the following issues:
- MIKE 3 AD (classic): Included option parameter 'ADStabilityValue' to improve stability of AD Scheme
- MIKE 21 MT (classic): Error in closure of MT output file resulting in loss of output data
- MIKE 21 & MIKE 3 MT (classic): Error in mean bed shear stress calculation in case of combined waves and very small current