Add support for more than two arguments to std.algorithm.setIntersection

This seems to have always been intended to work, but was left unfinished.
The old documentation, as well as the current entry in the cheat sheet,
claimed it supported any number of arguments.
Merge pull request #1796 from JakobOvrum/setintersection

Add support for more than two arguments to std.algorithm.setIntersection
fix property enforcement
Merge pull request #1799 from 9rnsr/enforceProp

fix property enforcement
Remove modules crc32 and std.md5 which had been deprecated by 6ff6adc5bf7d13b33e27985c53377cd20d7648e6
Merge pull request #1800 from Geod24/remove-deprecated-modules

Remove deprecated crc32 and std.md5
Revert "Remove modules crc32 and std.md5 which had been deprecated by 6ff6adc5bf7d13b33e27985c53377cd20d7648e6"

This reverts commit ecbc04f90d21303fd72d9ecfd501df15f49515a2.
Merge pull request #1803 from monarchdodra/revertDeprecate

Revert "Remove modules crc32 and std.md5 which had been deprecated by 6f...
add std.file.setAttributes