Remove debug print
Missing write barrier making test frames
More comments, & a robustness for toString
SVM col names; propagate ex's out of parser

SVM lite parser uses actual col count instead of estimated col count for
headers.
Use postGlobal() in DParse instead of H2OCallback to allow exceptions &
assertions to propagate to caller
Bug fixes in the sparse chunks

Implement inflation.
Handle len >32K.
Remove debug prints.
Merge branch 'master' into cliffc-sparse