Merge 'Fix cli comments parsing' from Diego Reis

#711
I followed the patterns that sqlite has, so everything after `--` is
treated as a comment. A bunch of spaces and a `--` is treated as a
comment also.

Closes #718

cli/app.rs

@@ -434,6 +434,9 @@ impl Limbo {
         line: &str,
         rl: &mut rustyline::DefaultEditor,
     ) -> anyhow::Result<()> {
+        if line.trim_start().starts_with("--") {
+            return Ok(());
+        }
         if self.input_buff.is_empty() {
             if line.is_empty() {
                 return Ok(());