Slightly better type errors for Unpackers.
Fixed upperbound and lower bound of IntAccept#acceptInteger(long).

Signed-off-by: Tsuyoshi Ozawa <ozawa.tsuyoshi@gmail.com>
Merge pull request #43 from oza/fixed-upperbound-and-lowerbound-of-readint

Fixed to check upper bound and lower bound of IntAccept#acceptInteger(long) correctly.