Attachments:
- Fix bug requiring click on attachment 1 to load any attachment
  urn:syndie:channel:d7:channel44:SjwUPvsAw05RyYIHuXy8xTEKKUq2rsb8Qu8zUDXoQ7I=9:messageIdi1358702772944ee
- Don't load attachments into memory unless displayable
- Don't keep attachment data in memory; reload if saving
- Set attachment tab text to file name
- Improve attachment tab layout
- Fix crash in some locales caused by SimpleDateFormat abuse