M2d Prepare code for new design

[timea-solid]

This work will include updated to HTML5 styles and accessibility elements. At the same time CSS files will be consolidated locally first.

[timea-solid]

See:

• profile-pane: Frontend refactor for profile profile-pane#100
• profile-pane edit part:
• solid-ui:
• source-pane:
• activitystreams-pane:
• chat-pane:
• contacts-pane:
• folder-pane:
• issue-pane:
• meeting-pane:
• solid-panes:
• mashlib :