[C2] CSS class per global page type

[ywarnier]

In order to customise the appearance of Chamilo, we need to introduce a CSS marker (a div with a specific CSS class) at the top of each page's content.

I can see the following pages:

• page-home
• page-my-courses (/courses)
• page-catalogue (/catalogue/courses)
• page-agenda
• page-tracking (with all sub-tracking pages under the same name)
• page-social (in general)
• page-account-security
• page-videoconference
• page-diagnosis
• page-administration
• page-administration-user (and other pages of that block)
• page-administration-course (and other pages of that block)
• page-administration-user (and other pages of that block)
• page-administration-session (and other pages of that block)
• page-administration-platform (and other pages of that block)

And optional:

• page-tool-document
• page-tool-exercise
• ...

The fact that it's legacy or not doesn't really matter, as long as the CSS class is placed correctly.