Support CSS classes macro-layout-section, single, two_equal, macro-layout-cell in the Confluence style sheet

[raphj]

These classes are used for layout in Confluence and get migrated, but if we don't support it the content looks messed.

[Farcasut]

• Updated the CSS to ensure that words wrap correctly and are displayed in a column instead of extending horizontally and causing a scrollbar
• Added support for up to 5 columns, matching confluence's current cloud version
• Added support for 2 left and 2 right sidebars when using a 3-column layout