Update parser.php

• When comparing your awesome updates against older versions in use, I find lots of random tabs/spaces before linefeeds. I've cleaned those up.
• A bit of code simplification, specifically the `getPart()` function, combining 6 or so functions into one.
• In the process, I cleaned up an inconsistency with `getPartContentID` vs `getPartContentId` in getAttachments()
• That's it, nothing massive :)