minor bugs corrected

2 bugs in mainWindow.py corrected (info pick emojis in linux freezed, path to .png)
also updated readme.txt with reference to emote (for Linux) and command to install python3-tk (for tkinter)

Minor update on requirements.txt

minor update: of requirements.txt due to:
GHSA-rhm9-p9w5-fwm7
moderate severity
Vulnerable versions: >= 3.1, < 3.3.2
Patched version: 3.3.2

First release

First release version containing basic set of features for demonstration purposes.