Add a launch argument for full screen (#663)

* per user config should be .gitignored

* add comment surrounding gitignore update

* make it wildcard

* add fullscreen to launch option struct

* remove redundant forward declaration and use fullscreen launch option in main

.gitignore

@@ -433,3 +433,6 @@ build/*
 
 # Local saves
 Minecraft.Client/Saves/
+
+# Visual Studio Per-User Config
+*.user