Wrap FileReader.onload in operation.

Issue #2406

- Adjusting indent of pasted block to current line
- Handle multi-line case, subsequent lines have their indent adjusted by their offset
to the first line.
- Add two tests for ]p to demonstrate this.
- Add [p to indent paste above

Added django.js which implements the following modes

  - django (text/x-django)
  - django:inner

Issue #988

Issue #2382

Issue #2360

Issue #2385

Conflicts:
	AUTHORS
	doc/compress.html
	doc/manual.html
	index.html
	lib/codemirror.js
	package.json

Issue #2355

Closes #2348