Startup and initialization

RigelEngine's startup and initialization consists of the following steps:

1. Command-line options parsing (main.cpp)
2. Load (or create) user profile
3. Initialize SDL
4. Create window
5. Create OpenGL context
6. Initialize Dear ImGui
7. Create Renderer
8. Load NUKEM2.CMP and create ResourceLoader. At this point the game will abort if it cannot find the resource file.
9. Create DukeScriptRunner and load all scripts
10. Load and resample all sound effects
11. Create initial game mode (depending on command line options)
12. Enter main loop