DRF-from-browser

Link to a DRF browser page from Inspect2.
Remove default constructors from H2OHexKey.
Support weaving docs for API subclasses.
DRF supports an initial random seed, better sampled-out asserts.
DRF supports NA's or dup records which cannot be predicted.
DRF scoring better supports untrained rows which do not land in any leaf
bin.
More robust debug printing.
Merge branch 'master' of github.com:0xdata/h2o
Merge branch 'master' of github.com:0xdata/h2o
Fix integration issues
Merge branch 'master' of github.com:0xdata/h2o