Parallel target execution / Progress information in console

[tunger]

This implements #162 and #107.

Main changes

• Redirect Logger output to InMemoryLogger instances per thread.
• Adds two build strategies: sequential and parallel
• Adds progress reporters:
  • Progress bar (ShellProgressBar) when running as console (i.e. not on redirected outputs)
  • Log per target: when running parallel on redirected outputs
  • Continuous: write logs as they come (current behavior)
• Adds BuildTimeEstimator to get sense of progress.

Usage

Opt-in to parallel build: Use ExecuteAsync in your NukeBuild class instead of Execute. Furthermore, if you provide the flag --no-parallel, it will always run sequentially.

Logger usage remains the same and is agnostic of threading from the view of the caller.

Open

• Test performance impact of progress bar.
• If there are lots of invoked targets, the progress bar grows from bottom of the terminal upwards, overwriting initial output.
• ParallelExecutionPlanner can very likely be improved.
• Commit 1b74097 is a fix for current problems on develop and can be removed afterwards.

I confirm that the pull-request:

• [x] Follows the contribution guidelines
• [x] Is based on my own work
• [x] Is in compliance with my employer

[tunger]

@matkoch please have a look at it if it is usable. It gets harder to keep it in sync with develop-branch and I consider it done from my part.

[matkoch]

I'm about to prepare the 0.25.0 release. Don't worry about develop. I will rebase this by myself. I'm planning to merge it for 0.26.0 then, but it could take some time.

[tunger]

Alright, thanks. Should you need a version of this branch before I rebased it let me know and I can restore it from my local computer - in case I accidently broke something.

[matkoch]

@tunger planned for v0.26.0 ... no worries about the conflicts.