support/scripts: add gen-manual-lists.py

Script generating the target and host package tables, and the deprecated
stuff list as well. These tables and lists are generated parsing the
Config.in files.

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

---
Chagnes since v3:
* Re-introduce try/except on the kconfiglib import. This is mandatory
  because the kconfiglib module is no longer embedded in the Buildroot
  source tree because of undefined license (the author wants to keep
  the authorship of his work of course, but he does not seem inclined
  to define any license on his project which would allow 3rd parties
  to re-use this project without any legal issues).

Changes since v1:
* many improvements, fixes, refactoring and cleanup (Arnout)
manual: add a make target 'manual-update-lists'

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

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Changes since v2:
* remove PYTHONPATH stuff since the kconfiglib module is next to
  gen-manual-lists.py (Arnout)

Changes since v1:
* add manual-update-lists target to the .PHONY one (Arnout)
* misc. fixes/updates
manual: cleanup appendix.txt

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

---
Changes since v1:
* move the surrounding text of the list back in appendix.txt (Arnout)
Makefile: add to the release target a warning about the manual updates.

The manual-update-lists target is not added to the dependencies of the
release target to allow editing the generated files.

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
manual: update generated lists

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

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Changes since v2:
* update lists