Create a module for modifying Halls

[ikolomiko]

The required methods for modifying the Halls in the database already exist in BLL::DatabaseHelper. However, there's no UI utilizing these functions.

• There should be a way to differentiate manually created Halls from automatically generated classroom Halls.
• The module icon might be this one
• The table widget in ikoOSKAR::UI::NSPreviewUi might become handy for displaying Halls
• The module should support basic operations such as:
  • Creating a new Hall
  • Deleting a Hall if it's not a classroom
  • Adding/removing Desks from a Hall