Update PROTEUS schematic

[stuitje]

Description

This PR updates the proteus_framework.md page with the new PROTEUS schematic via JSDeliver. For the light+dark switch and correct size, a new stylesheet is added; this is extra.css.footnotes.css has been updated to remove redundant configurations meant originally for SPIDER.

It also adds a silent title toproteus_framework.md silent, and updates the Atmodeller+FastChem links. PLATON has been removed.

Validation of changes

Built the site locally on safari, firefox and chrome.

Checklist

• I have followed the contributing guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have checked that the tests still pass on my computer
• I have updated the docs, as appropriate
• I have added tests for these changes, as appropriate
• I have checked that all dependencies have been updated, as required