Minify assets for --release builds

[thedodd]

This primarily applies to:

• SASS/SCSS (minify) (see Cut over to sass-rs, as it is a feature complete sass/scss solution. #14)
• CSS (minify)
• HTML (minify)
• PNGs (discussion below)

[svenstaro]

How about also optimizing PNGs?

[thedodd]

Sounds good to me. I’ll add it to the list above. Any ideas on libraries/algorithms we can use to accomplish this? I can’t say I’ve done much PNG optimization, I’d have to do some research on it.

[thedodd]

We can add a new pipeline handler which handles PNGs specifically and does optimization as part of the pipeline.

[svenstaro]

Seems like oxipng is absolutely perfect for this task.

[MartinKavik]

We need to minify also Rust/WASM.
For instance, the difference in *.wasm file size between wasm-pack and Trunk for one my Seed app is ~700 KB in release mode.
This minification is related to #5 because we would need to use wasm-opt.

[thedodd]

@MartinKavik agreed. Release mode still makes a big difference, however there is no wasm-opt integration quite yet. We definitely need to get that added in.

[mpfaff]

How about minifying the generated JavaScript?

[Carlrs]

Tried implementing this, but the JS minifiers I found on crates.io had problems - one broke wasm-bindgen generated JavaScript and the other couldn't parse it properly, but the author seems fairly active on github so I created an issue on his parser.

Will create pull request for CSS and HTML, but JS will have to wait and I feel that's the biggest bit.