Fix BitArray.opCmp
Fix codestyle code review comment
Fix code review comment: repcace some ifs to one expression
Use core.bitop.bsf in BitArray.opCmp for more efficient
Fix out of bounds.
std.bitmanip: BitArray.opcmp unittest improvements by MartinNowak
Merge pull request #2248 from Safety0ff/rebootpr1589

Reboot PR #1589: Fix BitArray.opCmp