add docs to install target
Fixes Issue 11222 - isNumeric should return false on -/+ as a single character.
Revert "Fix for issue 11108"

This reverts commit c930d8bd5e5246653a0300aac791b4c82b0466c5.
fix issue 11232 - rewritten std.windows.syserror.sysErrorString

Fixed for Unicode-correctness; now works on non-English Windows systems.
Made nothrow.
Added unit test.