4teamwork/ftw.mail — pull request #19 by jone (2014-05-12 16:21:02+00:00)
Title: Performance improvements

I've made some performance improvements.

Statistics of times the message is parsed with the email library per mail object:

| View | Before | After |
| ------------- | ------------- | ------ |
| Details view | 14 | 1 |
| Tabbed view mails listing (1 access) | 4 | 3 |
| Tabbed view mails listing (2..n access) | 4 | 0 |

I've added persistent (!) caches, which are set / invalidated when setting the message:
- Title
- Attachment informations
- Headers (on access)