Code improvements

Fix for preprocessing under a rare case where parallel calls are made by Qlik

README.md

@@ -97,6 +97,7 @@ _Note that this SSE and Docker do not handle file locking, and so do not support
 3. Download this git repository or get the [latest release](https://github.com/nabeel-qlik/qlik-py-tools/releases) and extract it to a location of your choice. The machine where you are placing this repository should have access to a local or remote Qlik Sense instance.
 
 4. Right click `Qlik-Py-Init.bat` and chose 'Run as Administrator'. You can open this file in a text editor to review the commands that will be executed. If everything goes smoothly you will see a Python virtual environment being set up, project files being copied, some packages being installed and TCP Port `50055` being opened for inbound communication. 
+     - Note that the script always ends with a "All done" message and does not check for errors. 
      - If you need to change the port you can do so in the file `core\__main__.py` by opening the file with a text editor, changing the value of the `_DEFAULT_PORT` variable, and then saving the file. You will also need to update `Qlik-Py-Init.bat` to use the same port in the `netsh` command. This command will only work if you run the batch file through an elevated command prompt (i.e. with administrator privileges).
      - Once the execution completes, do a quick scan of the log to see everything installed correctly. The libraries imported are: `grpcio`, `grpcio-tools`, `numpy`, `scipy`, `pandas`, `cython`, `pystan`, `fbprophet`, `scikit-learn`, `hdbscan`, `skater` and their dependencies. Also, check that the `core` and `generated` directories have been copied successfully to the newly created `qlik-py-env` directory.
      - If the initialization fails for any reason, you can simply delete the `qlik-py-env` directory and re-run `Qlik-Py-Init.bat`.