[PATCH guilt] make guilt use standard POSIX shell

This patch series makes guilt be able to work with a standard posix shell.

This has been tested with bash, zsh, dash and posh acting as /bin/sh.

This uses awk and sed a bit more than before, but POSIX awk and sed should be enough. Though GNU find and GNU /bin/echo from the coreutils needs to be there.

Here is the shortlog:

	Pierre Habouzit (7):
		  Regression test suite needs bash, that's OK.
		  guilt(1): Obvious bashisms fixed.
		  guilt(1): simplifications...
		  guilt(1): reimplement push_patch, using a subshell to avoid locals.
		  Easy commands, without bashisms.
		  guilt-status(1): Remove bashisms.
		  Remove last bashisms from remaining commands.

and the diffstat:

	 guilt                       |  448 +++++++++++++++++++------------------------
	 guilt-add                   |    7 +-
	 guilt-applied               |    4 +-
	 guilt-delete                |    4 +-
	 guilt-export                |    6 +-
	 guilt-files                 |    6 +-
	 guilt-fold                  |    4 +-
	 guilt-fork                  |    6 +-
	 guilt-graph                 |   13 +-
	 guilt-header                |    4 +-
	 guilt-help                  |    6 +-
	 guilt-import                |    6 +-
	 guilt-import-commit         |    6 +-
	 guilt-init                  |    4 +-
	 guilt-new                   |   15 +-
	 guilt-next                  |    6 +-
	 guilt-patchbomb             |   10 +-
	 guilt-pop                   |    4 +-
	 guilt-prev                  |    4 +-
	 guilt-push                  |   16 +-
	 guilt-rebase                |    4 +-
	 guilt-refresh               |    4 +-
	 guilt-rm                    |    4 +-
	 guilt-series                |    6 +-
	 guilt-status                |   58 +++---
	 guilt-top                   |    4 +-
	 guilt-unapplied             |   12 +-
	 regression/010-init.sh      |    1 +
	 regression/011-no-repo.sh   |    1 +
	 regression/020-push.sh      |    1 +
	 regression/021-pop.sh       |    1 +
	 regression/022-applied.sh   |    1 +
	 regression/023-top.sh       |    1 +
	 regression/024-unapplied.sh |    1 +
	 regression/025-new.sh       |    1 +
	 regression/026-delete.sh    |    1 +
	 regression/027-refresh.sh   |    1 +
	 regression/050-series.sh    |    1 +
	 regression/060-files.sh     |    1 +
	 regression/Makefile         |    2 +-
	 uninstall                   |    7 +-
	 41 files changed, 317 insertions(+), 375 deletions(-)