Add git maintenance files

[ace-dent]

Changes to make external contributions easier:

• Extend .gitignore for OS files (easier for new contributors).
• Add .gitattributes to normalize line endings.
• Bonus: Update Copyright year.

[MLXXXp]

I'll consider adding the .gitattributes file, after researching it a bit.

However, I don't want to put anything in .gitignore that pertains to a specific O/S or editor. I feel those should remain as global or working directory settings on the user's own system.

[ace-dent]

The .gitignore literally ignores those files on one's local copy. It just means they won't be accidentally committed. It also avoids any committer needing to remove them (locally) when preparing a commit. This stuff is just a nice Quality of Life touch for external contributors. :-D

[MLXXXp]

But where does it end?

I use Linux and my editor adds a ~ to the end of a filename to create a backup. Other editors might use a .BAK extension. Someday, another OS might be supported by Arduino, which has its own local files that should be ignored. People might use an IDE that can compile for Arduino, which has it's own specific config files, etc. in its local working directories.

I don't want to have to keep extending the library's .gitignore every time a new possibility arises. External contributors are expected learn Git well enough to maintain their own .gitignore file(s) as required by them.

Plus, it's better that the filenames you've included be added to the user's global .gitignore_global file, since it's very likely they should be ignored for all projects using Git.

[ace-dent]

Thanks @MLXXXp for feedback. After ~decade of using Git, I didn't know this could be set globally! ...You don't know, what you don't know!... I have removed the .gitignore changes.