Improve inject() in bundler

[asherber]

@rpatters1 Not sure if you wanted to review this.

The inject() function in the bunder, which inserts HashURL and RTFNotes, was assuming that there would only be one line in plugindef() that starts with return and one line that starts with end. This is not necessarily true, since a line of text in Notes, for example, could start with either of these. (And the Notes in the script I recently added did!)

This PR changes inject() to get the last matching token. There's still an edge case here if plugindef() does not include a return statement (since it's not technically required) but does have a line starting with return in Notes. But since this repo seems to have an unofficial requirement for a proper plugindef() function with a return, I'm not worried about this.

[asherber]

BTW, I ran the bundler locally, and there were no changes to the generated dist files, as expected.

[rpatters1]

I'm cool with it if it works.