Fix #425: Exact semantics of Int (arithm modulo 2^32).
Merge pull request #436 from sjrd/exact-int

Fix #425: Exact semantics of Int (arithm modulo 2^32).
Fix #430: Store StackTraceElement column in magic field
Abstract file output for packager and optimizers
Make virtual files fully path-aware (for identification)
Fix #427: Fully abstract JS virtual machine (and some along-the-way improvements)
Merge pull request #437 from gzm0/cleanup-runner

Cleanup runner
Remove dead code and cleanup imports in tools+sbt-plugin+build.
Merge pull request #439 from sjrd/remove-dead-code

Remove dead code and cleanup imports in tools+sbt-plugin+build.