Fix regression that broke error reporting for save to disk for books that contain no formats. Fixes #1405674 [Save to disk, ValueError too many values to unpack](https://bugs.launchpad.net/calibre/+bug/1405674)
Verify existence of installers after stage2
version 2.14.0
Retry listing of running VMs to handle transitory failures
DRYer
Simplify stage2 logic
MOBI Input: Fix incorrect conversion of MOBI files that wrap their content inside <a> anchor tags. Fixes #1405858 [A mobi file will not display or convert properly](https://bugs.launchpad.net/calibre/+bug/1405858)
Conversion: Convert images encoded as data URIs in the input document into normal images, as some ebook reader software cannot handle data URIs. Fixes #1405803 [Can't see images in *.mobi in Kindle after convertation](https://bugs.launchpad.net/calibre/+bug/1405803)
...
Driver for Papyre 624 ml

Fixes #1405901 [calible don`t detect papyre 624 ml](https://bugs.launchpad.net/calibre/+bug/1405901)
Ensure encoding to JSON doesn't crash if a datetime is inserted into field_metadata