Add KeyringUnlocker widget

Update Contributions section in README.md

Update installation instructions

Fix Makefile to install pavolmon.1

Add Makefile and man pages

Fix BatteryMonitor tests

Fix installation instruction

Restyle README.md

Add common options to each widget.

Remove duplication from README.md

Simplify widgets implementation and registration

Add information about default values for settings

Add Temperature widget

Add documentation for the Window widget

Add Window widgt

Update example configuration in README.md

Describe the Volume widget in the README.md file

Add Volume widget

Set slog.DefaultLogger()

Update example configuration in README.md