Replace “xmlinfo” guts with Expat XML parser implementation

* Byte order is incorporated into encoding field
* Input is a byte buffer
Use built-in functions for encoding text in XML, HTML and URLs
FTP.ntransfercmd() seems to do the job of the GrailFTP class
Use built-in “unittest” framework rather than custom one
Use quit() method over abusing SystemExit

The SystemExit exception gets mangled on the way through Python 3’s TK
library.
Use asterisk for runtime string formatting parameter