Update support for dir=auto in the README

* Gecko has had support since version 20.
* Internet Explorer is the only major modern browser not to support this
  attribute value and Blink now exists so just mention lack of support in IE.
README typo fixes
Fixes #5 - Remove deprecated captureEvents (used for Gecko prior to version 3)

This method has been a no-op for years.
Merge pull request #108 from mnoorenberghe/readme_updates

Readme updates
Merge pull request #109 from mnoorenberghe/captureEvents

Fixes #5 - Remove deprecated captureEvents (used for old Gecko/Netscape)