Define a load order method and use it in the dsda and eureka flags.

Also coerce the type of the complevel arg to string; subprocess won't
handle that for us.

dcc/eureka.py

@@ -15,7 +15,7 @@ class Eureka(dcc.doom_base.WadMap):
         if parsed_args.main is not None:
             mw = pwadpath.joinpath(parsed_args.main)
         else:
-            mw = sorted(list(pwadpath.glob('*.wad', case_sensitive=False)))[0]
+            mw = self.load_order()[0]
 
         complevel = self.complevel()
         port = "vanilla"