mdb_load wasn't properly inserting escaped backslashes into the data.
mdb_dump wasn't escaping backslashes when generating printable output.

Avoid stomping on flags from 1st readhr invocation

Orivej Desh authored Nov 22, 2015 and Howard Chu committed Nov 23, 2015

mdb_load -T was supposed to read escaped text, but 21b51cb7 "Add mdb_load"
made it read hex.

Off-by-one in end check, would complain on valid input.