Fixing how the Lexer handles text.

Scanning a file has all the lines terminating with a '\n' newline
character, but when giving the text directly to the lexer via the
scan_text function it should not append a newline at the end if there
was no newline in the original input.

src/lexer.rs

@@ -170,6 +170,13 @@ impl Lexer
          cursor.column = 0;
       }
 
+      // Remove the last newline character if the text did not end with a
+      // newline.
+      if !text.ends_with('\n')
+      {
+         stream.pop();
+      }
+
       Ok(transform(&stream))
    }