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.

NOTE: Minetest 0.4.14-dev or 0.4.15 required.

NOTE: Minetest 0.4.14-git or 0.4.15 required

Update craft recipes (fixes #66)

that use xpanes nodes as craft items

Also fixes a linter warning.

Fixes #51 

`tiles` is not a required field. Indexing it may fail.

Fix #51