Appveyor: fixed generation of artifact

before_package: scripts to run *after* solution is built and *before*
automatic packaging occurs.

Up to v0.9.0

Merge pull request avTranscoder#219 from cchampet/patch_v0.8.1

Patch v0.8.1

Up to v0.8.0

Up to v0.7.0

Merge pull request avTranscoder#202 from cchampet/fix_GhostThreadInPy…

…Thumbnail

Fix ghost thread in pythumbnail

Transcoder: fix seg fault on fillProcessStat call for generated streams

Warning: update API of StreamTranscoder.

Merge branch 'develop' of https://github.com/avTranscoder/avTranscoder …

…into develop

Up to v0.5.12

Up to v0.5.11