* Remove sudo package installation from demo scripts
* Change the build_dir path (benchmark_app.sh, squeezenet_download_convert_run)
* Remove redundant pip_binary
* Revert 'inference_engine_samples_build' as the build folder for .bat
* Add check for python 3.8
* Update help messages
* Use `model-optimizer/requirements.txt` instead of `install_prerequisites.sh`
* Add `--user` for python package installation (demo_security_barrier_camera.sh)
* Add python venv creation
* Create venv in $HOME instead of $ROOT_DIR
* Make the step messages look the same as in the .bat scripts
* Make the same changes to demo_benchmark_app.sh as in other .sh scripts
* Remove a mention of FPGA from a help message
* Set venv folder to `venv_openvino`
* Fix unknown command line flag errors if -sample-options is used
* Fix raw escape sequences output with dashes
* Fix raw escape sequences output with run_again message
* try change sampleoptions to array
Dmitry Pigasin