Fix custom resolver URL previews

Treat DOI and shortDOI previews independently as to whether the full
preview should be shown or just the last 10char + code.
Version 2.1.3

Also, convert manifest.json to unix line endings.
Whitespace and readme update

-Tabs for html, css, js
-Spaces for scripts
-Newlines at end of files

Only English is supported for now.