Add commands for doing common build tasks

[WebFreak001]

• [ ] For Windows: Make Desktop App/Hide Console (-L/SUBSYSTEM:windows)
• [ ] For Windows: Include icon in exe
• [ ] For Linux: Create freedesktop .desktop file
• [ ] Support #include with D++
• [ ] Run Unittests with Coverage (dub run -b unittest-cov)
• [ ] Show profiling report in d-profile-viewer (dub run -b profile)
• [ ] Enable betterC (dflags in dub)
• [ ] Enable DIP25 Sealed references / return ref (dflags in dub)
• [ ] Enable DIP1000 Scoped Pointers (dflags in dub)
• [ ] Enable DIP1008 Exceptions and @nogc (dflags in dub)
• [ ] Generate AST JSON (dmd -X)
• [ ] Use gladeD