If workbench disabling.
And setting for disabling:
- Chess
- Cooking
- Enchanting
- Hive
- Itemframe
- Mailbox
- Mechanisms
- Rope
- Workbench
By default all active.

Caused by a keystroke used in the formspec - this causes all
these fields not to be set, and the subsequent crash.

Luacheck points out that:

```
Checking src/workbench.lua                        1 warning
    src/workbench.lua:74:2: loop is executed at most once
```

And this is correct, only the pickaxe is actually currently
repairable.

Returned the code to the previous (working) fashion.