Fix remaining Java compiler warnings, mainly around missing
generics or deprecated code.

Also add the `-Werror` compiler option to ensure that any future
warnings will fail the build.

Issue: SPR-11064

Update the exception message used when Assert.instanceOf fails such
that it expects the provided message to end with '.'. This reverts
commit 5874383e which caused the
implementation to be at odds with the JavaDoc and the previous
release.

The updated code also has the benefit of protecting against a null
message.

Issue: SPR-10269

Issue: SPR-10128

Issue: SPR-9439

This renaming more intuitively expresses the relationship between
subprojects and the JAR artifacts they produce.

Tracking history across these renames is possible, but it requires
use of the --follow flag to `git log`, for example

    $ git log spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history up until the renaming event, where

    $ git log --follow spring-aop/src/main/java/org/springframework/aop/Advisor.java

will show history for all changes to the file, before and after the
renaming.

See http://chrisbeams.com/git-diff-across-renamed-directories