Fix in computing tree stats for GBM trees.
added some Exec2 testing and more stressful gz compression ratio
Added some basic operations like logical AND/OR
Graph Java API little bit polished.
Var imp name tooltip.
Fix in computing tree stats.
Merge remote-tracking branch 'origin/master' into drf2
WIP Adding cut method to ExecQuery2
Merge branch 'master' of https://github.com/0xdata/h2o
Cleanup fvec compression

Major comment upgrade.  Allocate side arrays in each Chunk.
Drop redundant min/max/hasFloat fields.
Drop redundant invalid/setInvalid calls.
Minor bugfix with setting NA into existing C0DChunk.
More cleanup of NewChunk

Allow Enums to compress any style; remove one 64K cap (may be more
limits).  Correct/cleaup _naCnt.  Tighter asserts, more comments.
Remove leaking Key from Bit-test
Uniformly cleanup enums & numbers

If the Chunk will be enums, nuke all the numbers.
If the Chunk will be numbers, nuke all the enums.
swap out tricky incremental math for simple bulk math

All rollups done in bulk at the start of NewChunk.compress().
Remove some commented-out code.