Make the% consistent across both Integer sizes.

[GregoryTravis]

There is no clear consensus about what % should mean when the first operand is negative.

The current behavior is that negative Integer values that fit in a Long return a negative result, while larger Integer values return a positive result:

IO.println (-9223372036854775807)%10
IO.println (-9223372036854775808)%10
IO.println (-9223372036854775809)%10

Gives

-7
-8
1 # Expected -9 here

For consistency, we'll return negative values for all Integer values. This makes it consistent with both Java, C, and C++ %.

(This is sometimes called remainder rather than modulo, but since programmers usually call this operator modulo we'll keep the original name of the method inside BigIntegerOps.)

Closes #9553.

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.

[JaroslavTulach]

OK.

[JaroslavTulach]

You may want to add more examples like those mentioned in the PR description.

[GregoryTravis]

Done.

[JaroslavTulach]

Where?

[GregoryTravis]

Sorry, I misunderstood you and added Examples to the documentation. Now I have added the example cases from the PR description.