Does not cover Vec's yet.

option method.
Remove commented out Firrterpreter
Since TreadleBackend is new code (based on FirrterpreterBackend) I
have made it scalastyle clean

Add chisel options to select backend
Made treadle the default
Added necessary glue to hook in Treadle
Changed build.sbt to add Treadle dependency

* Generalize ChiselAnnotation

This allows us to delay creation of Annotations till elaboration is
complete. Also update all annotation-related code.

* Add RunFirrtlTransform

Use a Chisel-specific RunFirrtlTransform API to preserve behavior of old
ChiselAnnotation (now called ChiselLegacyAnnotation)

* Use unique test directories in ChiselRunners.compile

Add companion objects to macro classes

Workaround for unconditional invalidation of macro classes in
incremental recompilation

* Remove checkboxes from issue/pr templates.

* Compact template text and try to make meta information comments.

* Respond to comments - remove bullet point usage.

Revert "Aggregate coverage - discover a working combination of aggregate usage to enable coverage of subprojects. (#782)" (#786)

This is still broken - it publishes multiple jars.
This reverts commit e08da912.

Aggregate coverage - discover a working combination of aggregate usage to enable coverage of subprojects. (#782)

* Generate aggregate coverage but publish a single Jar

* Reduce the aggressive dis-aggregation as it breaks super project aggregation.

* trying to get aggregate coverage working again ...

* Use the right incantation to enable aggregation for only the coverageReport task.