Maintenance ticket for ICU 62

Creating this ticket for cherry-picking various fixes into the maint/62 branch.
https://github.com/unicode-org/icu/tree/maint/maint-62

As per the discussion in the TC call on 2018-07-26, we are not going to bump up the version number, but will simply cherry-pick fixes into the maint branch so that users can download the source code with all the various fixes applied.