New development release (build 169)

[Arno Gerretsen] [ModelConverterX]
* Changed check for update functionality, so that in a stable release it does not check for new development releases, unless the user asks for it.
Fixed issue 790

[Arno Gerretsen] [ModelConverterX]
* Added options for default layer and visibility used in the ground polygon wizard
Progress issue 782

[Arno Gerretsen] [ModelConverterX]
* Fixed crash when entering day number 0 in ground polygon wizard for seasons
Progress issue 776