1.5.6: Highlight CPU Time and user names

In both px and ptop output.

1.5.5: px: Add --no-username switch

For use with fzf process killings with previews, try this for example:

px --sort=cpupercent --no-username | fzf --preview='px --color {1}' --bind 'ctrl-r:reload(px --sort=cpupercent --no-username)' --height=20 --no-hscroll --tac --no-sort --header-lines=1 | awk '{print $1}' | xargs kill -9

Ref: https://github.com/walles/px/issues/88#issuecomment-945099485

1.5.4: Fix --sort=cpupercent crash with Python 3

And add a regression test for it.

1.5.3: Add px flag for sorting by CPU usage only

Example: px --sort=cpupercent

The default behaviour, without this new flag, is still to sort processes by
relevance, based on CPU usage, memory usage and how recently they were started.

This release also fixes core counting on large Linux machines.

1.5.2: Improve ptop responsiveness

This release improves the general responsiveness of ptop.

If you try holding down down / up arrow this release should get you a more
pleasant experience than the previous.

Changes include but are not limited to:
* Do system polling (processes, memory, ...) in a background thread
* Pause process updating while scrolling with cursor keys
* Check terminal window size only after resizes

1.5.1: ptop: Improve screen updating code

In this release, the screen updating code:

* Is faster CPU wise

* Never clears the whole screen, but rather just overwrites changed lines. This
  should reduce flicker on laggy remote connections.

* Only updates changed lines. Should improve redraw experience on laggy remote
  connections since redraws now require fewer bytes sent over the wire.

1.5.0: ptop: Add system IO load display

Added to the header. It shows the IO device (among drives and network devices)
that has had the highest average throughput since ptop was launched.

1.4.1: Improve Perl command line parsing

Perl: https://github.com/walles/px/issues/85

This release also fixes a race condition: https://github.com/walles/px/issues/84

1.4.0: Binary size and startup time improvements

Binary startup time is now down from 460ms to 160ms on my test system.

Binary size is down from almost 800kB to 260kB.

This was achieved by replacing pex with my own home grown implementation
that relies on functionality already built into Python.

1.3.1: Performance tuning

ptop: Previously the sort order of the first displayed frame was quite different
from all the others, leading to a resort between frame 1 and 2.

In this release, the first frame and the rest of the frames are sorted much more
alike.

Internally, process listing performance has been improved, leading to a somewhat
shorter initial startup time and lower CPU usage for ptop itself.