The texture array used by WS30 requires that all
component textures be the same size and format.
This commit adds an alpha channel to those
png file used as primary textures in materials.xml
files which did not have one.
- Re-factor common properties (including condition statements) into separate files.
Note that using "index=0" attributes these can be over-ridden.
- Add caribbean regional textures and building definitions
- Add missing low-resolution rainforest-hawaii.png
