non-linear ray tracing

[Kwasniok]

• [x] #42
• [x] ray -> ray segment
• [x] ray interface e1f8a30
• [x] remove backgrounds 4ebcf1f9
• [x] #47
• [x] tmp: camera emmits rays a5d9694
• [x] make render geometry dependent 86ad7ae
• [x] add metric to hit record cb4ec85
• [x] remove euclidean based entities 9aa264d
• [x] add triangle entity b70b9ef
• [x] #44
• [x] extend geometry interface by ray_from af501f3
• [x] fix scattering f28d992
• [x] #46
• [x] Euclidean test 401dfda
• [x] #45
• [x] redesign camera a259805

[Kwasniok]

use separate repository

[Kwasniok]

new approach