ticket:9880: add ImmutableIndex, replace Chinese hacks and support zhuyin, handle index characters with multiple primary weights, lazy-create rarely-used objects, bug fixes, port other improvements from Java

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@33245 251d0590-4201-4cf1-90de-194747b24ca1