Merge pull request #25 from rubo77/header-links

backlinks to mainpage in header
Merge pull request #24 from rubo77/nodecolor

Offline nodes in grey instead of red
Merge pull request #26 from rubo77/header-links

backlink to mainpage onhover:underline
show labels for each node, hiding any overlapping labels
geomap tooltips with node name
Mark nodes with uplink