extend functions to use RandomAccessRanges
Trivial documentation fix for issue 12557

gcd is implemented with Euclid's algorithm, not Euler's algorithm.
https://issues.dlang.org/show_bug.cgi?id=12557
Merge pull request #2152 from WalterBright/path-randomaccess

std.path: extend functions to accept RandomAccessRanges
Merge pull request #2168 from gyrovague/master

Trivial documentation fix for issue 12557