Fixed bug in parser's _getinput() method: will now corrrectly stop
appending items to list, before the bug cause operands to "disappear"
under some circumstances.
Parser can now create final UIs with nested modes.
Parser can propagate global options without arguments to nested modes
(with plural options being incremented if they are found also in nested
mode), and singular options with arguments (which are not overwritten if
were passed to nested mode).
Updated test suite (tests for new features, and one new just-bug-catching test)