added prefix/suffix arguments to fix wolph#168

making sure we run all the finish code. fixes wolph#162

improved tests

added tests to prevent problems like wolph#157

extended samples tests

fixed bug wolph#154 "Progress bar display does not update", again...

fixed docs build for newer sphinx releases

updated appveyor python version

fixed tests for new flake8 release v3.34.4

Bumping version for signed releases using gpgit v3.34.3