Bug: parser fails to detect inline attachments

The parser completely ignores inline attachments.
For example, the message [1] includes a reference to an attachment, but it is not shown in the list view, only in the source view.

Compare withe the mod_mbox version [2], which shows the attachment

It might make sense to display the message structure in the same way as mod_mbox.
This would also allow easy access to HTML alternatives, which are also currently hidden.

[1] https://lists.apache.org/thread.html/918b4a61add01902e2dfbf1a17ba945b7d721e9cdf9d0235d374eb1d@1250786123@%3Cuser.zookeeper.apache.org%3E
[2] http://mail-archives.apache.org/mod_mbox/zookeeper-user/200908.mbox/%3c4A8D7B4B.5020701@apache.org%3e

Start by comparing the linked message and mod_mbox example, then trace how the parser represents attachments and how the list view renders message structure. Done means inline attachments and HTML alternatives are visible and accessible in the list view, consistently with mod_mbox.

Written by the indexing model from the issue text.