Remove all uses of toStringNow.
Remove all uses of std.metastrings.Format.
Remove the long-deprecated and undocumented std.perf.
Issue 5924 fix
Merge pull request #1171 from jmdavis/metastrings

Remove all uses of std.metastrings from Phobos
Merge pull request #1172 from andralex/5924

Fixes Issue 5924
Merge pull request #1170 from jmdavis/perf

Remove the long-deprecated and undocumented std.perf.