Clean up control interface

[wagneral]

The area below the monitor controls seems to claim to much space compared to the rest of the interface. It would be great if this area could be divided in a section with three (or more) tabs.

These tabs can contain the following elements, that already exist:

• share
• upload
• url

[dennmuel]

Download button for screensharing could be included in the first tab ("share") to make it more prominent.

[wagneral]

Control interface restructured. Tabs added, download button for screensharing included in first tab. Maybe add a fourth tab later on, for uploaded files. Maybe show uploaded original files in upload tab (dropzone).