Adds clear button for almost every <input type="text">, like ms-clear.
This script adds clear button for almost evey text-field in web site without breaking its layout, like ms-clear.
The clear button is displayed on the right side (or left side if text-align=="right") of the inside of the field when the mouse cursor is over the field.
The clear button does not work if the web site puts some elements (such as submit button) on the clear button's place (e.g. search form in Twitter).
