scanner: remove the "too long name" error; checker: check string() cast arg

vlib/compiler/scanner.v

@@ -1002,7 +1002,9 @@ fn good_type_name(s string) bool {
 // registration_date good
 // registrationdate  bad
 fn (s &Scanner) validate_var_name(name string) {
+	/*
 	if name.len > 15 && !name.contains('_') {
 		s.error('bad variable name `$name`\n' + 'looks like you have a multi-word name without separating them with `_`' + '\nfor example, use `registration_date` instead of `registrationdate` ')
 	}
+	*/
 }

vlib/v/checker/checker.v

@@ -591,6 +591,9 @@ pub fn (c mut Checker) expr(node ast.Expr) table.Type {
 		}
 		ast.CastExpr {
 			c.expr(it.expr)
+			if it.has_arg {
+				c.expr(it.arg)
+			}
 			return it.typ
 		}
 		ast.CallExpr {