Testing, error checking, argument changes
- Attempting to fix border removal from Unreal Engine 3 games that don't
  like it, such as Ride To Hell and Flashback; Slightly more info on
  line 317 of Program.cs
- Added error checking on PID-based borderlessing, it will now write to
  console and exit if the PID's "main window" as reported by
  System.Diagnostics.Process doesn't yield a usable handle for whatever
  reason
- Added GWL_EXSTYLE related externs, mostly for the above UE3 junk, but
  also because it might be handy later
- Changed -fs to --fs to stick to standards I guess and added --fullscreen
  and -f