Change PokemonBuilder interface to something cleaner

PkmnLibSharpTests/Battling/PokemonBuilderTests.cs

@@ -24,8 +24,9 @@ namespace PkmnLibSharpTests.Battling
         {
             var lib = BattleLibraryHelper.GetLibrary();
             var pokemon = new PokemonBuilder(lib, "testSpecies", 50)
-                .WithNickname("cuteNickname")
-                .Build();
+                {
+                    Nickname = "cuteNickname"
+                }.Build();
             Assert.AreEqual("cuteNickname", pokemon.Value.Nickname);
             pokemon.Dispose();
         }
@@ -35,7 +36,9 @@ namespace PkmnLibSharpTests.Battling
         {
             var lib = BattleLibraryHelper.GetLibrary();
             var pokemon = new PokemonBuilder(lib, "testSpecies", 50)
-                .WithGender(Gender.Female)
+                {
+                    Gender = Gender.Female
+                }
                 .Build();
             Assert.AreEqual(Gender.Female, pokemon.Value.Gender);
             pokemon.Dispose();