System-monitoring-center

* Several improvements (performance, security, bug fixes, etc)

* Improvements for error handling and dialogs (Startup tab)
* Removed unused dialogs
* Minor code comment changes
* Added information of number of Python packages (System tab)
* fix: dynamic updating of CPU core count and max frequency
* Reduced data update latency on tab switch (Process Details window)
* fix: search bug for services (Services tab)
* Various minor improvements (settings, GUI, etc.)
* Several changes for easier maintenance
* Fixed Processes tab right click menu bugs
* Improvements for performance summary on the headerbar

* Minor updates for function repeating mechanism
* Automatic data units are set for Floating Summary window
* Minor internal and GUI improvements
* Processes tab customizations menu simplifications
* Reduced CPU load while application start and tab switch

* Update README.md
* Minor GUI improvements
* Removed Run Application window which needs more detailed work
* Updated translation files

* Remove search customization features for simplicity

* Added support for viewing Arch Linux and pacman packages information
* Minor design changes on GUI icons
* Update README.md