Improve compatibility with application bundlers

[skozin]

This PR allows eccrypto to be used with bundlers that package Node.js app into a single executable (specifically, with nexe/nexe). There are two changes.

Avoid using return outside of a function

Node.js allows out-of-function return due to the way globals are implemented (it wraps all modules into a function), but it's not a correct JavaScript. One of the side-effects of this is that bundlers like nexe don't work with applications that use eccrypto. Bundlers use AST parsers like Acorn to parse all sources into AST and then combine them into a single JS file, and parsers choke on an out-of-function return.

Use .node extension when requiring native module

Bundlers that support bundling native modules, like nexe, need to know which require calls load native modules. To distinguish them from usual require calls, nexe looks at the extension which the require'd path ends with, and assumes it's native module if it ends with .node. Currently, eccrypto requires its native lib, ./build/Release/ecdh, without the extension, which prevents nexe from handling it specially.

[skozin]

Not sure why browser tests fail, it appears to be not connected with the code changes.

[JBaczuk]

This needs to be rebased from 1.1 and retested, the browser tests have been fixed in the 1.1 branch.

[boxfox619]

i have problem like this error

Module parse failed: 'return' outside of function (25:4)
You may need an appropriate loader to handle this file type.
| console.error(e);
| console.error('Reverting to browser version');
| return (module.exports = require("./browser"));
| }
| }

So, i remove the return statement in node_modules before bundling.
I tried to make a PR but it was already here.
I hope this PR will be reflected soon.

[shrpne]

I have the same error.

Can it be rebased and merged, please?

[Vitomir2]

Lol, why are these fixes left so long? @JBaczuk @skozin