Separate user supplied options from yeoman default options

[desidia26]

Feature:
Currently to access user supplied options/options that the author of the generator defines, that author must reference the this.options object. This object contains what looks to be yeoman internal data such as

`

env: Environment {

_events: [Object: null prototype] { error: [Function] },

_eventsCount: 1,

_maxListeners: undefined,

arguments: [],

options: {},

adapter: TerminalAdapter { promptModule: [Function] },

store: Store {

  _generators: [Object],

  _meta: [Object],

  _packagesPaths: [Object],

  _packagesNS: [Array]

},

runLoop: Queue {

  queueNames: [Array],

  __queues__: [Object],

  _maxListeners: 0

},

sharedFs: Store {

  _events: [Object: null prototype] {},

  _eventsCount: 0,

  _maxListeners: 0

},

lookups: [ '.', 'generators', 'lib/generators' ],

aliases: [ [Object] ],

sharedOptions: { sharedData: {} }

`

It would be helpful to separate these from user/author defined options so that option validation could be done more easily.

Use case: I have a generator where I wish to check and see if the user has passed an argument that I don't account for, and notify them.

[desidia26]

Closing, as I see this likely belongs against the generator repo. Apologies.