4042: task.foreach should now accept multiple parameters and generate tasks
based on the cartesian product of all input lists.
4042: Add support for filter and group of lists
4042: Fix syntax error
4042: list handling bugfix
4042: add "extract"
4042: Add list index
4042: fix bad syntax
4042: fix bad keys
4042: add command pattern to list index
4042: expand list fix
4042: another expand fix
4042: Start working on run-command reference page.
4042: Getting started on run-command reference
4042: Subst will raise exceptions if files/directories don't exist.
4042: Functions defined in get_items() now moved into expand_items()
4042: First draft document complete, need to verify that examples all work.
4042: Add dry-run mode to run-command.  Test and fix examples from documentation.
4042: When listing directory, return list of absolute paths
4042: Rename bad reuse of 'p' to 'match' in expand_item.  Finish describing
$(task.outdir).  Clarify that list functions take a user parameter name.  Fix
other spelling and grammatical errors in documentation.
4042: Update documentation samples.  Small fix to dry-run to allow supplying custom TASK_KEEPMOUNT.