- Converted the 'cal' command to TDB2.
- Reinstated command line handling for 'cal' command, but realized there
is a conflict with filters. Filtering disabled for 'cal' until a good
solution is found.
- Converted recur.cpp to use TDB2, which eliminates the file locking
problems that occur when both TDB and TDB2 are in use at the same time.
This will cause other issues until all commands are converted to TDB2.
- 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.
