Android: Apply weights to boxes as well as items. We have to update the weights whenever we add or remove something from a box that has already been packed, so adding a private boxUpdate method for doing that. I tried to clean up the existing code somewhat in the process but it caused other layout problems... so I went bare bones with the changes here and it seems to work. Will revisit the streamlining later.

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=3
DW_MINOR_VERSION=2