change 'password' to more generic 'mask'. Fix tab behavior

examples/password.rs

@@ -21,8 +21,8 @@ fn main() -> io::Result<()> {
 
     let mut textarea = TextArea::default();
     textarea.set_cursor_line_style(Style::default());
-    textarea.set_password_mode(true);
-    textarea.set_placeholder_text("please enter your password");
+    textarea.set_mask_char('\u{2022}'); //U+2022 BULLET (•)
+    textarea.set_placeholder_text("Please enter your password");
     let layout =
         Layout::default().constraints([Constraint::Length(3), Constraint::Min(1)].as_slice());
     textarea.set_style(Style::default().fg(Color::LightGreen));