Changes needed to use crossbuilder on manjaro + other

manjaro:
- If no 'dpkg' command found, try to determine host architecture using
  other metod(s).
- Don't check for 'dpkg-architecture' command at beginning. Run the
  command in container, if missing.
- Don't check for 'dpkg-parsechangelog' command at beginning. Run the
  command in container or replace it by using grep+sed, if missing.
- Run lxd daemon at startup, if not running.
- Use current user/group id in lxd subuid/subgid setup & assurance.
- If not 'apt' found, check for 'pacman' and use if present.
- If container is missing network access, try to apply 'dhclient' hack.
  and then check again for network.

other:
- Fix unset usage.
- Fix some missing -e in echo where needed.
- Add some echos, before running some commands.
- Minor alignment fixes.
- Don't use 'newgrp' upon lxd install, seems to have no effect.
- Don't detect host architecture, if HOST_ARCH is already set.
- Unify command output redirection formatting.
- Make some multi-line commands to be in one line.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "dpkg"]
+	path = dpkg
+	url = https://github.com/davidben/dpkg.git