Logging: allow to setup default log output in global

[jkellerer]

Fixes #261

Adds a new option to define the default log output in global:

global:
  log: 'some-destination'

Adds a new destination syntax - for the case that:

• global redirects to a file
• you want to redirect to console or stdout instead (- means "console or stdout")

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (63f8faf) 77.42% compared to head (f6547d0) 77.48%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #277      +/-   ##
==========================================
+ Coverage   77.42%   77.48%   +0.06%     
==========================================
  Files          97       97              
  Lines       10284    10283       -1     
==========================================
+ Hits         7962     7967       +5     
+ Misses       2043     2037       -6     
  Partials      279      279              

Flag	Coverage Δ
unittests	77.48% <ø> (+0.06%)	⬆️

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

Files	Coverage Δ
commands_display.go	40.45% <ø> (+0.76%)	⬆️
config/global.go	86.36% <ø> (ø)

... and 1 file with indirect coverage changes

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[creativeprojects]

It looks good to me, thanks 👍🏻

I tried windows elevation and the logs are going through fine 😛

That was also one of the last bits missing for the run-schedule command, cool 😎

[creativeprojects]

I was thinking... at some point we might want to distinguish regular commands and interactive commands like self-update because it doesn't make much sense to send the output somewhere else than the console 😐

[jkellerer]

Yes. Though these commands might still use log as is but output the important information to stdout / console instead of using log (which is mostly the case already, might just need a review)