ticket:10646: Add documentation to Template class.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35005 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10646: Introduce PluralTemplate class. Have RelativeDateTimeFormat use it.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35009 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10646: Add documentation to PluralTemplate class.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35010 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10646: Change PluralTemplate C++ class to match JAVA QuantityFormatter class.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35012 251d0590-4201-4cf1-90de-194747b24ca1