Don't allow method names to overflow.

test/method/call_name_too_long.wren

@@ -0,0 +1,4 @@
+// Don't want to actually execute it.
+if (false) {
+  0.thisIsAMethodNameThatExceedsTheMaximumNameLengthOf64CharactersBy1 // expect error
+}

test/method/long_name.wren

@@ -0,0 +1,7 @@
+class Foo {
+  thisHasAMethodNameThatIsExactly64CharactersLongWhichIsTheMaximum {
+    return "result"
+  }
+}
+
+io.write(Foo.new.thisHasAMethodNameThatIsExactly64CharactersLongWhichIsTheMaximum) // expect: result

test/method/name_too_long.wren

@@ -0,0 +1,5 @@
+class Foo {
+  thisIsAMethodNameThatExceedsTheMaximumNameLengthOf64CharactersBy1 { // expect error
+    "body"
+  }
+}