Patch Jun 24

Uploaded a patch:

• Got ISBN code from the National Library, updated the code wherever it appears.
• Changed puzzle 65: there was a sneaky unintended solution that completely bypassed the leftmost piece.
• Changed puzzles 69 and 70: 70 allowed for an output of a single column that could still make the needed output in 71; changed 69 solely because of the aesthetics, to fit besides 70.
• Changed puzzle G, because a missing worker completely broke the whole F-I sequence. (How the hell did I miss that!)
• Some small typos, updated solutions, etc.

Also, added 50 more free community copies.