app_terminal.py:  Changed how the 'linkpath' value is determined in order to better support situations where Gate One is embedded into other web apps.  This should allow things like PDF downloads when Gate One is running on a different server/port from the page it is embedded into.
gateone.js:  Added a helpful logError() message for when a ping timeout occurs.
gateone.js:  Disabled the overlay feature since Firefox fires the 'blur' event far too often--especially when it doesn't make any sense whatsoever.
terminal_input.js:  A few modifications here and there to fix the problem where you can't highlight text in Firefox.
Themes:  Minor adjustments to the global prefs panel.