Simple snippet autocompletion

[davepagurek]

Autocompletion entries should be a Map<RegExp, string[]>, where the regex matches the string up to the cursor. The strings are code snippets that the user can then change.

e.g.

entries.set(
  /Color\.$/,
  [
    'Color.fromRGB(r: 255, g: 255, b: 255)',
    'Color.fromHex(#FF0000)'
  ]
)

[davepagurek]

Possibly we want to implement our completion in ACE as "snippets"? https://cloud9-sdk.readme.io/docs/snippets