We're not including anything above `main.js.in`, so the top of that file
always ends up as the top of the final user script. We don't need a
separate build step to include it.

Forgot to comment out the Mousetrap license in the final build file.

Don't need Browserify. Just concatenate the user script header and the
compiled `main.js`.

Rebuild the `peniquitous.user.js` user script file.

We're no longer using the `require` imports to include JS files. Instead
we have a template string process. Not as robust, but easier to fit what
the final user script needs to be.

Since this file has template variables, it's not a real executable
JavaScript file. Add `.in` to the end to make it clear it needs to be
built with Make.

Instead of copy-pasting the code from the files directly into main.js,
do it in the build recipes.

The keyboard event simulation didn't work. Tried getting rid of
Browserify and including the JS all in one file, but that didn't make a
difference. Committing this for reference.