terminal.js:  Fixed a bug where terminal screens would be filled with lines containing the word, "undefined" over and over again at initial creation.
terminal.js:  Re-worked how the screen is drawn slightly in order to improve rendering performance.  Will make the most difference with larger terminal sizes and certain embedded situations.
terminal.css:  In conjunction with the rendering changes, added the ✈termline class and made it "display: block;" so that paint events would take place in smaller chunks.
gateone.js:  Added GateOne.Utils.debounce() (it's a copy the one from underscore.js).
terminal.py:  Just a minor fix to a docstring.