Deprecate InlineCasts, add InlineAcrossCasts

[jackkoenig]

To maintain binary compatibility, InlineAcrossCasts is just aliases to
the now deprecated InlineCasts. We can make the binary incompatible
change of renaming the class and object for 1.5.

I will do a follow on PR to do the actual class and object rename for 1.5 (might as well delete LegalizeClocksTransform then too).

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• [NA] Did you update the FIRRTL spec to include every new feature/behavior?
• [NA] Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you state the API impact?
• Did you specify the code generation impact?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• documentation
• code refactoring

API Impact

This deprecates InlineCasts, renaming it to InlineAcrossCasts to make it more clear. This transform is very unlikely to be used.

Backend Code Generation Impact

No impact

Desired Merge Strategy

• Squash

Release Notes

Deprecate InlineCasts, renaming it to InlineAcrossCasts

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels?
• Did you mark the proper milestone (1.2.x, 1.3.0, 1.4.0) ?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you mark as Please Merge?

[seldridge]

Looks great.

I did not double check that all uses of InlineCastsTransform were properly migrated, though.

[jackkoenig]

I did not double check that all uses of InlineCastsTransform were properly migrated, though.

I did 🙂