Tag printing with debug to infer purity
Add non-debug purity unittest
Correct typo
Use debug printTree() instead
Remove debug calls to printTree from within printTree itself
Tag unittests at global scope as pure
add @safe annotations to all unittests which 'just work'
Mark std.uni.MultiArray.this with array types as safe, pure, nothrow and nogc
Make std.concurrency compatible with fibers

https://d.puremagic.com/issues/show_bug.cgi?id=12090

With this commit fibers can have own message boxes and act similar
to threads in that regard.
Add Generator to std.concurrency

Generator is an extension to a Fiber that yields return values of specific type
Merge pull request #2617 from nordlow/pure-rbtree

Tag printing in rbtree.check() with debug to enable purity inference
Merge pull request #1910 from complexmath/addConcurrencyScheduler

Issue 12090 - Make std.concurrency compatible with fibers as threads
Merge pull request #2632 from braddr/safe_range

add @safe annotations to all unittests which 'just work'
Merge pull request #2633 from tom-tan/safe-pure-nothrow-uni-MultiArray-this

Mark std.uni.MultiArray.this with array types as safe, pure, nothrow and...
some doc fixes
Merge pull request #2634 from burner/getopt_doc_fix

some doc fixes https://issues.dlang.org/show_bug.cgi?id=3780
some doc updates and some more testing

moved examples to unittests

DmitryOlshansky fix
Merge pull request #2630 from burner/array_replace_doc

some doc updates for std.array and some more testing