LIB-52: verify sectors given to put()

The first element in the array is the overall disc length, which must
be bigger than everything else.
All offsets have to be smaller than a maximum.
LIB-52: verify offset order and test verification

Some common errors should definately be catched.
We can't catch one important thing: The length of the array.
This hopefully triggers one of the other problems, too.
Merge branch 'verify_put'

see pull request #35 and LIB-52