Create dictionaries from user-provided wordlists

[Helium314]

Convenient as it avoids having to use dicttool_aosp.jar.

But this seems to have issues with large dictionaries (~400k words) that should be fixed.
Ideally we'd just compile the word list as the dicttool does, this would allow larger dictionaries.
Alternatively large lists could be split.

A draft because

• needs some way of dealing with large word lists (fjxing the problem, splitting the dictionary, or compiling to .dict file)
• needs better parsing (at least bigrams and shotcuts, maybe also accept a simplified format)
• crappy dialog when adding because we should inform user about problems. Ideally it would just be done in background, though not sure what happens if the user tries to use the dictionary or closes the app while words are still being added
• I'm not going to continue in the near future (other things with more priority), but to anyone interested: feel free to take over