version 3.2.1 released

[Mark Perry]

I couldn't get the current 4.x branch to work on JRE 6, so I have released 3.2.1 that targets version 6 of the JVM.  There are no functionality changes for this release.

Release notes are at https://github.com/functionaljava/functionaljava/blob/master/etc/release-notes/release-notes-3.2.1.adoc.

Mark