This must prevent the useless download of bt5 which are already installed
And so this is supposed to reduced the number of bt5 installed by configurator and make it faster

- duplicated default categories were dropped when the list of categories was
  passed without their base categories
- accept any iterable for 'category_list'

Also simplify sample HTML in test_safeHTML_conversion

this leads to a difference between generated cache id for set and get for *same* function call
thus eliminating image caching.
Examples of generated cache ids:
(get) -> 39600:5:formatpngquality45.0
(set) -> 39600:5:displayNoneformatpngquality45.0

This is a fix for 841b0206 which started to
return "" for empty cells, whereas it's supposed to return None.
This also fixes the 20 minutes slowdown introduced when parsing a category
spreadsheet, such as in the first page of configurator.

This reverts commit 991a6467.
Module is already allowed without this change.

The same mistake seem to be present in other parts of this test.

This reverts commit fccf5f8c.

This test is not passing yet, mark it as expected failure, or
wait to commit it... find a way to not show errors, we do not
have regressions here

fixup: ERP5Site_reindexAll now reindexes everything all tools in portal and all ERP5 Python Scripts under portal_skins.

remove ERP5 Python Script reindex code from ERP5Site_reindexAll for now, that does not work in bootstrap.
this commit partially reverts adee3e48.

check only if the new catalog does not miss anything, because the original catalog before reindexAll can be imperfect by other tests, that are bad though...

fix ERP5Site_reindexAll so that it reindexes everything having getUid and also ERP5 Python Scripts under portal_skins.

and improve test_13_ERP5Site_reindexAll to check if list of paths is exactly same.

Person subobjects are not needed after first pass, so don't
waste time indexing them.

Preferences were reindexed early, because they are needed
to index documents requiring access to a conversion server.
This must not be required to reindex users (which just happen
to be Person documents so far) as they are needed to index
security properly and categories.