Slightly more correct shim for Node.textContent

First draft, but closer to the spec:
http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#Node3-textContent

- No longer uses Element.innerText as a setter, since there were
  undesirable side effects (recursive node modification, ew).
- Works with Text nodes as well now.
- Still needs to work with non-text, non-element nodes (e.g. cdata,
  comment, etc..), and to handle error cases as described in the spec.
- (Would be nice to have tests, but maybe that's something for the
  plugin as a whole...)
Build aight.js and minified file
Flesh out Node.textContent shim a bit more

Now works with non-text, non-element nodes (e.g. comment, document
fragments, etc.) as well as weird IE elements that somehow have
different behaviors (e.g. script, style, etc.).

Fixes shawnbot/aight#27.
Element's textContent should exclude comments
textContent of a BR element should be a line break
Merge branch 'node-textcontent-shim' of github.com:usmonster/aight into usmonster-node-textcontent-shim

Conflicts:
	aight.min.js
Merge branch 'usmonster-node-textcontent-shim'
version 1.2.5 with pull #27