Remove unused code
Fix formatting
Extract code to display error/status messages to a separate method
Fix russian translation of 'message_view_no_viewer'
Remove old/unused code from click handler
Make all fields of AttachmentView private
Rename method and improve documentation
 Create named class for loading and displaying attachment thumbnails
Split 'populateFromPart' into multiple methods
Remove "m" prefix for field names
Clean up comments
Inline method
Rearrange fields/methods
Fix method names/visibility
No longer pretend there are attachment types we don't care about
Extract intent creation code to method
Try original and inferred MIME type to find best viewer for attachment

In order for Android to find apps that are capable of opening an attachment for
viewing the ACTION_VIEW Intent needs to contain an appropriate MIME type.
Ideally, we'd use the MIME type specified for the attachment in the message.
But often the supplied MIME type is wrong/useless. So we look at the file
extension to try to come up with a sensible MIME type on our own. We then go
on to ask Android which of the two MIME types leads to more apps claiming to
be able to open our attachment for viewing and use that one.
Use MIME type used for intent resolution in content provider
If we can't find an app to view an attachment try again with a file:// URI

Sadly, some apps only support the 'file' scheme in their intent filters. Among
them is Android's own package installer.
Append file name to content:// URI

This allows intent filters with patterns for file extensions to match.