Extend compatibility tests

docker: centos-8 powertools repo name changed

with more comments and fix binaries dir path.
Add release step to remind to update compatibility tests with new releases.

cmake: add ROOT_DIR and make use of CURRENT_*_DIR variables

Update CMake and package's version in name

and move this piece of code to a helper function.

Fix coverity issues (not catching exception in dtor)

Bump required version of libpmemobj

Since introducing flat_transactions, 1.9 is needed.

readme: update readme file

- update instructions for Windows build using VC++2015
and disability to build with radix_tree
- minor readme changes

Fix SRCVERSION in CMake

ref. #597

and if source ver can't be established, set it to "generic" project's VERSION.

CI updates and fixes

Properly find Valgrind on OpenSUSE

CI: remove redundant CMake param in Windows build

Introduce flat transaction class and change containers' behavior

and make sure to skip only Valgrind tests, not for all tracers.

And update check in run-build.sh to test if build really fails.

major CI/utils cleanup

ref. 02c0feca

and make sure WORKDIR env is set.

it's useful for debugging, especially if tests fail.

Pushing image happens only on push events so tests are expected to pass.
Taking this into account - pushing can be done right after rebuilding
an image, instead of marking a flag for a later push.

- set proper IMG_VER on stable branches,
- use "rebuild" param (for pull-or-rebuild.sh) on stable branches.