Mark std.range.cycle for static array and their unittests as system
Extend groupBy to handle non-equivalence relations.

Update DDocs.

Add unittest for 13595.
Use flag enum instead of bool.

To prevent Boolean Blindness.
Do reflexivity check in assert mode if predicate is claimed to be equivalence relation.
Use Flag instead of single-use enum.
Rename IsEquivRelation to EquivRelation.
make nested foreach over TypeTuple bodies into lambdas to avoid huge functions
Merge pull request #2767 from rainers/unittest_smallfuncs

Reduce compilation time for phobos unittests by about 25%
Use version-specific navbar when building docs.
use ElementType consistently
Merge pull request #2775 from e10s/patch-3

std.range.package: use ElementType consistently
Use -prerelease for navbar ddoc instead of hardcoded version.
Merge pull request #2654 from quickfur/issue13595b

Issue 13595: Extend groupBy to handle non-equivalence relations.
add upgrade hints
Merge pull request #2777 from WalterBright/upgrade

add upgrade hints
Merge pull request #2769 from tom-tan/system-range-cycle-for-sarray

Mark std.range.cycle for static array and their unittests as system
Merge pull request #2774 from quickfur/versioned_navbar

Use version-specific navbar when building docs.
Fix broken ddoc build for std/regex/package.d.
Update std.range.* docs.

The previous docs were simply dissected from the original std.range docs, and
the text in each module is truncated and awkward to read. The main package.d
docs were also missing links to the submodules. So, update the docs to reflect
the current state of things.
Fix broken PHOBOSSRC link.

This is caused by Ddoc's "helpful" auto-highlighting of every occurrence of the
name of the module, including places where it's not very helpful.