When running a sbt script, this change lets the user on UNIX and
Windows platforms to use native file extensions like none/.sh or
.bat/.cmd. The code copies the file to the sbt boot/hash/src_managed
directory with a .scala extension.
Provides a workaround flag `incOptions :=
incOptions.value.withIncludeSynthToNameHashing(true)` for name hashing
not including synthetic methods. This will not be enabled by default in
sbt 0.13. It can also enabled by passing `sbt.inc.include_synth=true`
to JVM.