spec tweaks, and add select_continue

[Bentheburrito]

Hello! Thanks for this lib, it's been very helpful in one of my projects as I learn Mnesia.

This PR fixes a couple of spec discrepancies dialyzer highlighted, adds support for :coerce in read/3, and adds Query.select_continue.

I hope you don't mind, I also added a .formatter.exs and formatted the project (a4214bc). Reviewing by these commits (with with actual functional changes) will be easier:

• 591fe4e spec changes, support :coerce in read
• bb108c2 adds select_continue

[sheharyarn]

Thank you for the PR!

This project was started before the Elixir formatter was created, and follows its own unique style-guide (which predates formatter). I do plan on updating the code formatting and style to use the modern formatter but that requires a bit of work from me before I'm ready to do that.

Would you be kind enough to update your PR to only include the code changes, spec tweaks, etc. without the formatting?

Thank you again!

[Bentheburrito]

That makes sense - I reverted the formatting changes in the last commit. Let me know if anything else should be changed!