Java 6 support and fix for UTF-8 under OS X

Hi @bodil, I'm really excited about this language. Shen-like without a crazy license!

I wanted to quickly play with it but ran into two problems under my environment.

---

## Specify file.encoding as UTF-8 in Lein project
    
Under OS X, I was presented with the following:
    
    BODOL version 0.0.0
    You are in a maze of twisty little passages, all alike.
    ??
    
I then tried to input:
    
    (ƒ triplet a b c -> (list a b c))
    
It looked right in the terminal but didn't parse correct. Specifying the Java file encoding to be UTF-8 fixed everything.

---

## Use Java 6 compatible symbol regex pattern
    
The `isAlphabetic` method only appears in Java 7. The Letter Unicode category (L) should hopefully be enough. The only case I can think that's left out is the 'Number, Letter' category which has things like Roman Numerals. I think that's fine to leave out.