Remove the frame argument from the builder, we can use the builder
allocated frames.
Add deref function to builder to make it more flexible later.
Add some more recursion depth checks in the parser.
Improve props filter, also filter other types.
using JSON for formats or properties is not a good idea because we can't
add more types like pointers, fd, rectangles without weird hacks. Our
PODs are more easy to parse and extend and now there is an easy way
to parse and create them as well.
