Removed duplicate autoAPISettings setting.
Updated key ID for signing Facsimile JAR files.
Corrected a couple of SBT build errors.

The PGP signing key is now entered correctly. Project names, instead of
project IDs, are used as the names of source sub-projects.
Updated to release 2.10.4 of scala.
Removed trailing whitespace.
Refactored duplication string resource keys into string constant.
Refactored duplicate string resource keys into string constants.
Fixed a bunch of Scalastyle magic number issues.
Removed redundant braces.
Corrected potential issue modifying mutable state.

Also overcame a Scalastyle warning.
Corrected a Scalastyle warning.
Addressed some Scalastyle warnings.
Tidied up use of synchronized in EventId. Overcame Scalastyle issues.
Updated SBT to release 0.13.2.
Removed redundant braces after package object definition.
Accommodated scalatyle warnings about mutable fields.

In this particular case, there appears to be no alternative to using
mutable fields.
Hardened thread safety accessing mutable fields.
Fixed scalastyle-highlighted issues.
Removed redundant braces following package object declaration.
Resolved Scalastyle warnings.