Use cached instanceof implementation in IVar creation

Significantly increases runtime performance of typed code. Runtime of a MethodScript program that computes the CRC32 of a size 250000 byte_array was reduced from 24.5 seconds to 4 seconds.

src/main/java/com/laytonsmith/core/constructs/IVariable.java

@@ -49,11 +49,9 @@ public IVariable(CClassType type, String name, Mixed value, Target t, Environmen
 		if(value instanceof CVoid) {
 			throw new CRECastException("Void may not be assigned to a variable", t);
 		}
-		if(!type.equals(Auto.TYPE) && !(value instanceof CNull)) {
-			if(!InstanceofUtil.isInstanceof(value, type, env)) {
-				throw new CRECastException(name + " is of type " + type.val() + ", but a value of type "
-						+ value.typeof() + " was assigned to it.", t);
-			}
+		if(!InstanceofUtil.isInstanceof(value.typeof(), type, env)) {
+			throw new CRECastException(name + " is of type " + type.val() + ", but a value of type "
+					+ value.typeof() + " was assigned to it.", t);
 		}
 		this.type = type;
 		this.varValue = value;