Add functionality for symbol-node

Additionally adds support for symbol-node as Text instead of
Parent.
Update Readme.md for Text punctuation and white-space
Update benchmark results in `Readme.md`
Update changelog for 0.3.0-rc.1
0.3.0-rc.1
Update eslint, mocha
Refactor to disallow space after object keys
Merge branch 'feature/add-symbol-node'

This merge incorporates a major change. A new SymbolNode
is added. Marks other than numerals or letters, or punctuation,
or white space, such as the copyright symbol or an ampersand, are now
classified as a `SymbolNode`.
Add `.eslintrc`
Update changelog for 0.3.0
0.3.0