Fix bug where getDirSize always return (0, 0) no matter the argument.

Add tests for database.extractData

See merge request !14

Make names of  UI code pep8 compliant

See merge request !13

Shorten all lines to 80 characters.

Remove commented code in calendar_dialog.py, channel_prefer_dialog.py,
mainwindow.py, time_power_squareddialog.py, and db_gui_superclass.py.

Change name of waveformdialog.py and plottingWidget.py to use snake_case.
Change a name in time_power_squareddialog.py to snake_case.

Make names in time_power_squareddialog.py and waveformdialog.py use
snake_case.

Make names in plottingWidget.py use snake_case.

Rename channeldialog.py, channelpreferdialog.py, dataTypedialog.py,
dbgui_superclass.py, paramdialog.py, and plottypedialog.py to use
snake_case
Rename variables and functions in above files to use snake_case

Rename calendarwidget.py to calendar_widget.py
Rename variables and functions in calendar_widget.py to snake_case

Ruler and zoom in TPS

See merge request !11

Time-power-square

See merge request !7

Plotting

See merge request passoft/sohstationviewer!6

Read and plot RT130

See merge request passoft/sohstationviewer!5

Read mseed and log data

See merge request passoft/sohstationviewer!4

Main UI and miscellaneous associated widgets

See merge request passoft/sohstationviewer!3

Gitlab CI pipeline and setup files

See merge request passoft/sohstationviewer!2