feat: in-memory mode

[aleclarson]

This commit makes the default export of sorcery a function. You must pass an array whose items must be a string or an object. String items must be the source code of a file with an inline source map. Object items must have a content string property, and an optional map object property.

The sorcery function returns a SourceMap object. Its file property must be set before calling toJSON if its associated file will be saved somewhere on disk.

You can pass an options object as the second argument, which takes the
same options as Chain.prototype.apply.

Other changes made in this commit:

• add sourceRoot property to SourceMap
• add decode method to Node
• use process.cwd() when node.file is null
• check for node.map in the getMap function

Closes #166

[aleclarson]

I should add options.resolve for resolving a source path (from the sources array of a sourcemap) into a content string or {content, map} object.

That would be useful if you do some transformations on individual files before concatenating them.

sorcery([
  // bundle sourcemaps go here
], {
  resolve(file) {
    // return {content, map} or a string here (supports async?)
  }
})

[aleclarson]

My fork of sorcery is now a major refactor of this repo.

I stripped out the CLI and anything filesystem-related.

It caters more to build tools, which work with in-memory files most often. So while intermediate files are supported, they are not the default.

[aleclarson]

I'm closing this, as I have no need for it to be merged anymore. 😄