Implement fixes for Luacheck 0.26.1

[Elv13]

• Rename or mute parameters starting with _
• Replace not (>=) with <

(note, this is mostly untested)

[codecov[bot]]

Codecov Report

Merging #3655 (1601c68) into master (05a405b) will decrease coverage by 0.01%. The diff coverage is 56.25%.

@@            Coverage Diff             @@
##           master    #3655      +/-   ##
==========================================
- Coverage   90.64%   90.63%   -0.02%     
==========================================
  Files         854      854              
  Lines       54775    54787      +12     
==========================================
+ Hits        49653    49657       +4     
- Misses       5122     5130       +8     

Flag	Coverage Δ
gcov	90.63% <56.25%> (-0.02%)	:arrow_down:
luacov	93.43% <56.25%> (-0.02%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
lib/awful/layout/suit/floating.lua	17.30% <0.00%> (ø)
lib/awful/layout/suit/magnifier.lua	66.25% <0.00%> (ø)
lib/awful/layout/suit/tile.lua	73.93% <31.25%> (ø)
lib/awful/menu.lua	57.48% <41.86%> (ø)
lib/ruled/client.lua	90.90% <50.00%> (ø)
lib/awful/key.lua	86.48% <60.00%> (ø)
lib/awful/screen.lua	92.99% <60.00%> (ø)
lib/awful/keygrabber.lua	82.86% <66.66%> (-2.85%)	:arrow_down:
lib/awful/tag.lua	78.97% <73.33%> (ø)
lib/gears/surface.lua	72.22% <92.30%> (ø)
... and 19 more

[Elv13]

All done