Rename submission to submission-restrictions

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Whitespace cleanup

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Extend model-solution to link to file and allow to consist of multiple files

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Make sure each indention level consists of 4 spaces

Signed-off-by: Sven Strickroth <email@cs-ware.de>