Add support for ESLint v2

[Daniel15]

I copied how Babel 6 is handled - Created "modules" under packages which export the correct version of ESLint. Moved shared code into a eslintUtils file.

Pretty much all the transform logic is identical across ESLint 1 and 2. I kept the transformers themselves (eslint1/index.js and eslint2/index.js) separate rather than totally sharing them (eg. a createESlintTransformer factory method) so that it's easier for them to deviate if needed.

[Daniel15]

Hopefully the npm package stuff is okay, I kept getting strange permission errors like this when running npm install:

npm ERR! Windows_NT 10.0.10586
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install"
npm ERR! node v5.7.1
npm ERR! npm  v3.6.0
npm ERR! path C:\src\astexplorer\node_modules\eslint2
npm ERR! code EPERM
npm ERR! errno -4048
npm ERR! syscall rename

npm ERR! Error: EPERM: operation not permitted, rename 'C:\src\astexplorer\node_modules\eslint2' -> 'C:\src\astexplorer\node_modules\.eslint2.DELETE'
npm ERR!     at moveAway (C:\Program Files\nodejs\node_modules\npm\lib\install\action\finalize.js:38:5)
npm ERR!     at destStatted (C:\Program Files\nodejs\node_modules\npm\lib\install\action\finalize.js:27:7)
npm ERR!     at FSReqWrap.oncomplete (fs.js:82:15)
npm ERR!
npm ERR! Error: EPERM: operation not permitted, rename 'C:\src\astexplorer\node_modules\eslint2' -> 'C:\src\astexplorer\node_modules\.eslint2.DELETE'
npm ERR!     at Error (native)
npm ERR!  { [Error: EPERM: operation not permitted, rename 'C:\src\astexplorer\node_modules\eslint2' -> 'C:\src\astexplorer\node_modules\.eslint2.DELETE'] parent: 'astexplorer' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.

It resolved itself if I ran the command again. I think it's just npm being glitchy and not an actual issue. (I've seen the same thing on Linux and on Windows so I don't think it's an OS-specific issue)

[fkling]

The problem with this is that the transitive dependencies, babel-eslint and babel-core are now loaded on every page load, not only when someone uses the eslint transform.

You could simply load the utils dynamically as well.

[Daniel15]

Oh, good catch! I thought Webpack would automatically make a new bundle for every transformers/*/index.js but maybe it doesn't work that way. How does the code splitting work? It is simply the require([..], cb) that does it? I've never used that feature of Webpack.

[fkling]

Yep, the require([..], cb) does the magic :)

[fkling]

Thank you so much for doing this!

[Daniel15]

Updated the diff to also dynamically require eslintUtils.