Describe the bug
Currently Portfolio Performance uses $HOME/.PortfolioPerformance/ for various files, please consider changing this to OS standards.

A small library for java can be found here: https://github.com/dirs-dev/directories-jvm

To Reproduce
Steps to reproduce the behavior:

1. Open Portfolio Performance
2. $HOME/.PortfolioPerformance is created

Expected behavior
Usage of XDG user directory spec on linux.

Desktop (please complete the following information):

• OS: linux
• Version 0.49.4