KDE Review: mimetreeparser

[Carl Schwan]

Hello,

I would like to move MimeTreeParser to KDE Review. I created an issue for 
tracking this here: https://invent.kde.org/pim/mimetreeparser/-/issues/1

The code is a fork of the mimetreeparser from Merkuro, which is in itself a 
fork of the internal library from Sink/Kube, which is in itself a fork of the 
mimetreeparser from KMail/Messagelib.

MimeTreeParser is split in a Core/Widgets/Quick component making possible to 
use it various KDE apps. My immediate uses is in Merkuro Mail (QtQuick) and 
Kleopatra (QtWidgets) to view encrypted emails, but in the future it would be 
great if more of our mail related projects would use it, as the MimeTreeParser 
contains a lot of complex code that we should try to avoid duplicating.

The code only rely on KMime, so it can be used with Akonadi, Sink or any other 
technology.

There is two examples built with the app, so you can play with it by running 
them:

./build/bin/mimetreeparser-widgets mail.{mbox,asc}
./build/bin/mimetreeparser-qml mail.{mbox,asc}

Just note that it doesn't support everything yet, in particular html email 
which is relies on QtWebEngine is not enabled in the demo and the 
mimetreeparser will prefer displaying the plain text alternative.

Cheers,
Carl