* Allow customizing max form size from env vars
* Add error page for unprocessable entities
And change default http port to 7878
* Improve char counter: under the editor, more discrete, and give it a default value
Rust can compile to WASM, so let's use it for front-end code as well.
To compile the front-end:
```
cargo install cargo-web
cargo web deploy -p plume-front
```