- Removed DOM caching, which appears to be a problem.
- Added 'id' and 'uuid' to DOM::get, which were missing, and therefore
caused all filters with sequences to fail.
- Modified CmdInfo to load all tasks, until TDB2 is here.
- 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.
