some slide in 3th unit + HintController
split to controllers, change hints work
Merge branch 'master' of https://github.com/kontur-edu/uLearn

Conflicts:
	src/uLearn.Web/Views/Course/Slide.cshtml
	src/uLearn.Web/Views/Course/_ExerciseHints.cshtml
	src/uLearn.Web/Views/Course/_SolutionControl.cshtml
	src/uLearn.Web/uLearn.Web.csproj