- Rewrote updateRecurrenceMask, which was hopelessly muddled after the
TDB -> TDB2 change.
- Modified associated code.
- Improved signal to noise ratio in unit tests.
- Converted the 'done' command to TDB2. This has a negative impact
on unit tests, but that represents bugs and ommissions in TDB2,
not flaws in the 'done' command.
- Eliminated stored arg_overrides and file_override in Context.
- Removed Filter, Subst, Task, Sequence from Context.
- Remove shadow file support. Hallelujah.
- Disabled/commented out most commands, ready for the big transition
to the new parsing style.
- Obsoleted Subst.{h,cpp}.
- Obsoleted Command::exectute 'commandLine' argument. It is worse
than unnecessary, it is an uncategorized raw argument string, which
is only really useful for the 'execute' command, which itself now
calls Arguments::combine to reconstruct the command line string.
