Unable to serialize coordinates as floats in combination with *Props

[santeripuranen]

Description:
It seems that an error in the PicklerOps::CoordsAsDouble mask value (introduced while fixing #2510) now unintentionally triggers serialization of coordinates as doubles (here) whenever any of the Props are selected for serialization, making it impossible for the user to select a combination of Props and coordinates as floats. Likewise, calling MolPickler::pickleMol with propertyFlags set to PicklerOps::CoordsAsDouble will also trigger AllProps serialization as a side effect. This behavior is less of a problem, though, as it can be dealt with on the caller side.

The fix:
Unless there's something I'm missing, simply changing the mask value from CoordsAsDouble = 0x0001FFFF; to CoordsAsDouble = 0x00010000; should correct both problems and make the code behave as expected.

[bp-kelley]

I think this makes good sense.