Add top-level variable to schala prelude

schala-lang/language/src/prelude.schala

@@ -1,3 +1,4 @@
+let _SCHALA_VERSION = "0.1.0"
 
 type Option<T> = Some(T) | None
 type Ord = LT | EQ | GT
@@ -9,6 +10,5 @@ fn map(input: Option<T>, func: Func): Option<T> {
     is Option::None -> Option::None,
   }
 }
-  
 
 type Complicated = Sunrise | Metal { black: bool, norwegian: bool } | Fella(String, Int)