Adding print! to the list of specially-formatted format!-like macros

[davidalber]

This PR adds new tests for #549 and corrects a typo from #2219.

• Added print! to the list of specially-formatted macros.
• Added tests for each instance of specially-formatted macros.

[davidalber]

Expand this snippet below to see that panic! appears in the list further below. Looking deeper now, though, panic! belongs in the part of the list since it is part of the Standard Library. Shall I add it back and keep print! here?

[topecongiro]

Yes please! And thank you very much for adding tests!

[davidalber]

I realized that I didn't add similar tests for each of write!, writeln!, and assert!. I'll do that, too.

@topecongiro: log! has syntax that is similar (at least visually) to write! and friends. Shall I add it in for special formatting with write!, writeln!, and assert!?

[topecongiro]

@davidalber Adding more tests is awesome, thank you! The link is to the old version of log! macro. The recent version of log! allows more complex syntax, so I think we shouldn't add it.

[davidalber]

I dropped the comments that indicate which macro is being tested because after adding so much duplication I feel the macro names jump out really clearly. I can add comments back if anyone feels strongly about it.

[topecongiro]

Thank you!