Bug fixes and multiprocessing

Fix bug where gain setting changes did not immediately reflect on sweep voltages
Make third octave band calculation faster by adding multiprocessing
Small improvements on text messages

Qt version 6

Move to Qt version 6
Improve settings storage
Add license info and about tab
Add setup.py

Improved logging and bug fixes

fix bug during sweeping more than 2 channels

Functioning file import and sweeper

v0.1.3

update README