COMPLETED

1.  Check for executable existance
        A. Check for Proton
        B. Check for Windows executable
    
    This would keep the program from executing programs that do not exist on
    the drive.


2.  Pass arguments to executable
        A. Pass arguments to Windows executable
        B. Dynamically change the amount of arguments passed to allow this 
        feature to be added.

    Make it possible to launch programs which need specific command line
    arguments to execute using Proton Caller. This is needed because many games
    and game launchers DO NOT run without spcial arguments. Some may want to
    use this to also force games to run in different graphics APIs 
    (OpenGL, Vulkan).


2.  config file for paths and default

    A. include and use library to parse config files
    B. Have paths to steam's common
    C. Have path to a default version
    D. choose default version if none listed

    Remove the need for confusing and inconsistant environment variables