Give sum a seed capability
Eliminate _assertPred
 Issue 5870 - Debug code in SortedRange assumes it can always print the range
Merge pull request #1970 from monarchdodra/sumseed

Give sum a seed capability
Update range.d
Merge pull request #2028 from Infiltrator/patch-1

 Issue 5870 - Debug code in SortedRange assumes it can always print the ...
Fix DDoc typo.
Merge pull request #2031 from monarchdodra/ScopeBufferConst

Fix DDoc typo.
Merge pull request #2017 from andralex/datetime

std.datetime: eliminate _assertPred