Fix html deprecations

[jbrichau]

Removes the use of tags and attributes currently deprecated (or non-functioning) in HTML5 from the Seaside tests and examples.

Also fix the wrong deprecation of:

• the th.scope attribute (it was only deprecated for td tags).
• the charset attribute on meta tags

Fixes #1418

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 77.41935% with 7 lines in your changes missing coverage. Please review.

Project coverage is 49.04%. Comparing base (d90609c) to head (ad52bec).

Files	Patch %	Lines
...Test.class/instance/renderInline.factor.key.on..st	0.00%	3 Missing :warning:
...sFunctionalTest.class/instance/renderContentOn..st	0.00%	2 Missing :warning:
...eFunctionalTest.class/instance/renderAnchorsOn..st	0.00%	1 Missing :warning:
....class/instance/renderCellForDate.row.index.on..st	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1434 +/- ## ========================================== - Coverage 49.09% 49.04% -0.06% ========================================== Files 9144 9143 -1 Lines 80565 80552 -13 ========================================== - Hits 39553 39506 -47 - Misses 41012 41046 +34 ```

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