XMLterm changes only.
Fixed xmlterm bustage due to build and nsIContentHandler changes (bug 91815).
Also modified xmlterm to handle terminal: protocol rather than telnet:,
to avoid conflict with telnet implementations (such as protozilla).
UI changes. If user has started typing in a new command, double-clicking a filename copies the filename to the cursor position, rather than opening/executing the file.
Minor tweaks to handle input of control characters. Switched to double clicks, instead of single clicks, to activate XMLterm features (to protect the user).
Improved full screen implementation; added bold and underline styles. Centralized UI event handling. Added checks to limit number of output lines displayed. Added capability to interrupt hung output data streams. Nearing full backwards compatibility with xterm.
