Evisum 0.5.0

Again with the downtime due to the pandemic, I've had some more time to work on Evisum. There was opportunity to completely restructure the source tree, as well as fix and improve on code for querying the various systems. There are some UI changes also. Everything in its own place (own window). Therefore, there is no restriction on access to available system and process information.

Highlights
Introduce a traditional application menu.
Add a CPU core viewer with rudimentary graphs.
Add filesystem querying API.
Support infinite sensors and batteries.
Take into account ZFS usage on FreeBSD systems.
Add documentation viewer in the process view.
Create a process window for processes (split the UI out).
View per-thread core usage of process.
Support threads on Linux, FreeBSD, OpenBSD and DragonFlyBSD.
Process argument parsing refinements.
Code refactoring of process and thread query API.
Fix memory leaks.
UI alignments and improvements.
Massive rearrangement of the source tree.
Indicate process list sorting.
Fix swap calculation on macOS.
Fixes for non-Linux machines on aarch64.
Allow user to attach to a process (no more excuses users!!!).
Add an about window.
Bug fixes.