Simplify the example a bit

[17cupsofcoffee]

Here's a few tweaks that make the example a bit simpler/up-to-date:

• A seperate wasm_main is no longer required due to Add first-class support for binary crates rustwasm/wasm-bindgen#1843.
• The prelude import wasn't actually being used anywhere.
• Nightly is no longer required to build this project, so I removed that from the instructions.
• --no-modules has been replaced with --target web, which doesn't rely on global variables and allows support for JS snippets.
  • The only caveat to this is that the generates JS is a ES module instead of a basic JS file - but any browser that supports WASM will also support ES modules, so I don't think this is an issue in practice.

[grovesNL]

This is great, thank you! I think the prelude used to be needed for wasm_bindgen(start).

bors r+

[17cupsofcoffee]

I think the prelude used to be needed for wasm_bindgen(start).

Ah yeah, that makes sense!

[bors]

Build failed:

• continuous-integration/travis-ci/push

[grovesNL]

The CI failure is unrelated, cargo-web fails to build on Rust 1.37.0. We'll need to bump it to a higher version and change the minimum Rust version in README.

[grovesNL]

It looks like Rust 1.38.0 stabilizes ptr_cast, so we can move to 1.38 as the minimum version. I think we just need to switch 1.37 to 1.38 in .travis.yml and README if you'd like to make this change.

[17cupsofcoffee]

Done!

[grovesNL]

Apparently cfg(doctest) (stabilized in 1.40) is also used in a dependency somewhere. Hopefully there's nothing else :/

[17cupsofcoffee]

Done (looks like xml-rs added the doc tests in a patch release about a month ago, and that's used by gl_generator) - third time's the charm, hopefully...

[grovesNL]

bors r+

[bors]

Build succeeded:

• continuous-integration/travis-ci/push