aatv: Fixes for rain-mode

Some rain-mode properties tried to read float from int value. Initialize rain after setting rain-mode. Rain was non-functional if width/height were left at default values.

I'm not sure about the logic to silently ignore user set properties. It is required to set them in the correct order without the user knowing about this. No idea about the general approach about these min/max range settings, perhaps setting the corresponding min/max partner to the set property is an alternative? Although that would again mean that one setting is automatically set without the user explicitly setting it.