Primitives for head/tail/index/cons/reverse/length now all assume the
char* is UTF8 encoded. Also updated generation of literals to encode as
UTF8. Primitives are probably not as efficient as they could be (though
some of the will be used rarely)
ASCII strings will work exactly as before.
Everything I know about UTF8 encoding has been learned in the past few
hours. Therefore, this is unlikely to be the best way to do this. Please
educate me, ideally in the form of annotated Pull Requests :).
