1) tiny Exec2 fix: ASTassign was missing -1 on row and col.
2) related change: Vec.set() will now close chunks immediately after EACH write. and so repeated calls to Vec.set() will be SLOW.That's because when invoking Vec.set(i,d), nobody holds a reference to the underlying chunk which should get closed when done with updating the it. Vec could keep the ref. to the last modified chunk, but I think it would be problematic (would have to be transient so it would get dropped by cleaner and so on).
Merge branch 'master' of github.com:0xdata/h2o