Fix HEX-1819 part 2: Vec.makeSeq and add JUnit test.  Was limited to ~8M
entries, now chunking into pieces to handle larger arguments.

Change makeSeq and makeConSeq length arguments to long instead of int.
HEX-1819: Modify ASTOp to take long arguments instead of int for makeConSeq and makeSeq calls.
Merge branch 'master' of https://github.com/0xdata/h2o