Big fix branch for 2021

[ianfixes]

There are a lot of interrelated things to fix, so this branch intends to be a heavy-handed attempt to combine all those fixes.

Highlights from CHANGELOG.md

• See CHANGELOG.md for more

Issues Fixed

• Fixes NoMethodError: undefined method `map' for nil:NilClass #295
• Fixes Line ending inconsistencies in cpp/arduino/avr/ files #283
• Supersedes Line endings #285
• Fixes Poor error reporting for undefined platforms #282
• Supersedes Fix problem with warnings for platforms #297
• Fixes Reporting compile errors in GitHub Actions #288
• Supersedes Use before(:each) rather than before(:all) #289
• Supersedes Demo lack of error report. #298
• Supersedes Convert files from CRLF to LF #286
• Fixes Allow test runner script to increase the default width, with a minimum #269
• Supersedes Hide build artifacts #290
• Addresses Unable to use library directory on Windows #280

[hlovdal]

I have two fixes you can cherry-pick from the branch 2021-02-15_beta.update. The first one is trivial, but the second one about the --path argument I am not sure if is correct, so maybe just use that as a reference to investigate what the correct commands should be.

With the crlf branch merged into master, you can drop the commit "Update CHANGELOG.md to describe line endings change." from this branch.

[ianfixes]

@hlovdal It doesn't look like there's too much to bring over ianfixes/arduino_ci@2021-02-15_beta...hlovdal:2021-02-15_beta.update

[ianfixes]

@jgfoster I'll try to break this up into smaller pieces so we can get it merged in, but I'm not sure which of the issues fixed (see PR description) are most pressing

[jgfoster]

@ianfixes, That's fine. As you have seen, I've merged most of my changes. The one remaining is the one to build a library once and use it for the remaining tests. While this has had an enormous speed improvement in our application, I'm not seeing the same improvement in the TestSomething case. For that reason I'm holding back and on merging it till I can better document the improvement.

As to the other PRs, I do intend to review them and merge them as I understand what is happening (I've given my own preferential treatment since I understand them!).

[ianfixes]

Pulled into #334 with the exception of 1ee342c

[ianfixes]

This has merged as part of #334 and was released in v1.4.0. 1ee342c is being tracked in #337