fix Issue 13645 - Incorrect ddoc generation for deprecated module
Merge pull request #4082 from 9rnsr/fix13645

Issue 13645 - Incorrect ddoc generation for deprecated module
remove std.math import

Reason: insnan is going to be deprecated in std.math.
Merge pull request #4090 from 9il/isnan

remove std.math import
fix Issue 12447 - variadic template functions hijack all eponymous enum and alias template overloads
fix Issue 11916 - [IFTI] Disabled by constraint overload with `out` with IFTI breaks overload resolution
fix Issue 11915 - Inconsistent overload resolution behaviour between `ref` and `out`