Solve conflicting "chunks" declaration
make ChunksImpl private
Mark the unittest for std.array.minimallyInitializedArray as @safe
Mark std.array.split and splitter as @safe and pure
Fixup for issue 9565

Remove unnecessary else block so right not it's never used.
Merge pull request #1605 from 9rnsr/fix9565

Fixup for issue 9565 - cleanup of #1544
Merge pull request #1483 from monarchdodra/chunksAmbiguity

Solve conflicting "chunks" declaration
Fix Issue 11152 - formatChar doesn't handle `\0`
Merge pull request #1576 from tom-tan/safe-pure-nothrow-array-split

Mark std.array.split and splitter as @safe, pure and nothrow
Merge pull request #1261 from denis-sh/add-lvalue-rvalue-traits

Add lvalue/rvalue traits
Merge pull request #1575 from tom-tan/safe-unittest-array-minimallyInitializedArray

Mark the unittest for std.array.minimallyInitializedArray as @safe
Merge pull request #1611 from monarchdodra/11152

Fix Issue 11152 - formatChar doesn't handle `\0`
Use documented unittests for `std.traits.isAssignable`.
[Refactor] Remove redundant parantheses in `std.traits.isAssignable` unittest.
Clarify documentation. Add `isRvalueAssignable` and `isLvalueAssignable`.

Previously `isAssignable` worked like `isLvalueAssignable`.

Also add some unittests.