Read strings using the standard library encode/decode instead of what I've got.

[andrew-vant]

Ideally, I should be loading a map file and doing whatever magic is necessary to get it registered as a codec. Then encode/decode from bytes to strings and back using the standard library functions. This may remove the dependency on patricia-trie, as well; it seems python has built in support for character maps, but I don't know if it will do the right thing with multi-character mappings.