Pharo13 + other development improvements

[jbrichau]

• Fixes the removal of the Author class in Pharo 13
• Moves the Seaside control panel to it's own main menu
• Adds the selenium setup for development (on Mac only for now)

This is a draft. Need to finish some things.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 9.75610% with 37 lines in your changes missing coverage. Please review.

Project coverage is 49.44%. Comparing base (0f7d6f7) to head (7e4444b). Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
...class/runSeleniumServerInTerminalMenuCommandOn..st	0.00%	9 Missing :warning:
...oControlPanel.class/class/seasideMenuCommandOn..st	0.00%	7 Missing :warning:
...olPanel.class/class/runSeleniumServerInTerminal.st	0.00%	6 Missing :warning:
...ntrolPanel.class/class/seasideIcebergRepository.st	0.00%	6 Missing :warning:
...rolPanel.class/class/controlPanelMenuCommandOn..st	0.00%	4 Missing :warning:
...atform.extension/instance/seasideSetAuthorName..st	0.00%	3 Missing :warning:
...velopment.class/class/ensureAuthorInitialsWith..st	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1450 +/- ## ========================================== + Coverage 49.42% 49.44% +0.02% ========================================== Files 9073 9098 +25 Lines 80086 80225 +139 ========================================== + Hits 39582 39668 +86 - Misses 40504 40557 +53 ```

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