- blob: check it, fix it (ref counting, serialization, etc.)
- drop dep on glib>=2.12.0 (due to base64)
- any type: make xdl compiler understand any type

- implement error codes in xdl-compiler (so that you can define errors in one
  place for whole interface)
- array<double>: too long to fit into i->data
- extend testsuite
