Use lowercase names for alphabetical order

Order of `keyPrep.txt` is inconsistent with the in-game sorting order of portals. This is because the game uses a case-insensitive sort, whereas the script uses a case-sensitive order. Fixed by generating the name-sorted index array based on lowercased portal names.

Before:
```
Kub (Palladio)
Kunst Voor Het Gemeentehuis
Modern Art Sofa
Pantaleon Jule 2007
kunst van wonen limburg
moskee panningen
```

After:
```
Kub (Palladio)
kunst van wonen limburg
Kunst Voor Het Gemeentehuis
Modern Art Sofa
moskee panningen
Pantaleon Jule 2007
```