Help has TTY detection

[mdm-code]

• Write help and errors to stderr
• Support tty detection in tcols CLI command

[codecov-commenter]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (aee6038) 90.33% compared to head (ca8ab5b) 87.84%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #3      +/-   ##
==========================================
- Coverage   90.33%   87.84%   -2.50%     
==========================================
  Files           3        3              
  Lines         238      255      +17     
==========================================
+ Hits          215      224       +9     
- Misses         17       25       +8     
  Partials        6        6              

Files	Coverage Δ
cmd/tcols/main.go	77.03% <50.00%> (-3.48%)	⬇️

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