Zhudi renders slowly

[lindenr]

Showing definitions can take a very long time, depending on the word. I did a bit of profiling and it turns out the _format_codes function is to blame, probably because it searches the whole db for every character. I think it would be better to do one db search on startup, and keep a dictionary of (character) -> (code) in memory. What do you think?

For now I've just made _format_codes return an empty string in my local build and it runs much faster! :)