Added SOSI logo & changed link from Jisc logo
Make project title links open in new tab
Added introductory text at top, though this should be made to look nicer
Updated button colour and font size in view-by-theme box
Steps towards adding node colour key
Symbols in colour key are now circles
Changed layout of NodeTagFilter and colour key, added explanation of node size
Merge sosi-viewer and resolve conflicts
Import from XML now adds/updates node colour