std.string: clean imports

update UUID

printf => trustedPrintf

added rd.uni selective import

needs for aliases

update global import

Revert "update global import"

This reverts commit 445d6b5fdc536ae8cc774aff9e28db0dfed3513e.

update global import

update unittest in windows.syserror

ditto

use safe printf("%s", str)

removed aliases and added public impotr

update docs

add local import to string.d