flag is sometimes set to -1 so needs to be signed
unsigned int offset can never be less than 0
unsigned int dep can never be less than 0
char will never be greater than 127
Revert "char will never be greater than 127"

This reverts commit 248fcf3bd7aea3cd499aac2c670e6c41c12a3b6b.
check if ascii codepoint is less than 0

ascii is a signed char so cannot be greater than 127
use MVMint8 to make this explicit
Merge pull request #132 from carbin/type-limits

Fix/remove comparisons that will always be true