ticket:10676: unum_open should support UNUM_CURRENCY_ISO, UNUM_CURRENCY_PLURAL styles

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35093 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10676: Also update the unum_open documentation for available styles

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35094 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10633: Implement context-sensitive number formatting (currently just for RBNF)

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35095 251d0590-4201-4cf1-90de-194747b24ca1