ticket:10646: Add documentation to Template class.

git-svn-id: http://source.icu-project.org/repos/icu/icu@35005 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10622 Fix warnings and errors when DEBUG is accidentally defined.


git-svn-id: http://source.icu-project.org/repos/icu/icu@35007 251d0590-4201-4cf1-90de-194747b24ca1