Remove useless lambda
Make imports scoped in functional
more std.functional import scoping
Merge pull request #1953 from monarchdodra/ArrayClean2

Remove useless lambda
Merge pull request #1956 from monarchdodra/functionalIncludes

Scope includes in std.functional
Fix Issue 11017 - Improve performance of toLower etc.

Changed to use `appender` instead of repeated `~=`.

https://d.puremagic.com/issues/show_bug.cgi?id=11017
Reserve appender length for the common case
Merge pull request #1957 from Poita/bug11017

Fix Issue 11017 - Improve performance of toLower etc.
Make std.stdio.testFilename @safe and pure
Merge pull request #1960 from tom-tan/safe-pure-stdio-testFilename

Mark `std.stdio.testFilename` as `@safe` and `pure`