Different lecture forms for different person types

[Bozydarek]

Required #60 first.

For sponsors, they should see what other lectures have been already proposed by their coworkers. And they should see their maximum guaranteed time (with some explanatory description, that they shared this time between all of them, they don't need to use full time, there might be option that we will approve longer lectures if their topics will be interesting).

For special guest. They should have access to choose longer lectures time plus maybe option to choose specific day for lecture if needed.