* Replaced some skyr functions with range v3, and removed some redundant code

* Added range-v3 to CI builds

* Disabled MSVC 2017 because of range-v3 support

* Resolved some missing directories from install step that were removed

* Removed a lot of redundant code from percent_encoding

* Fixed missing header in json.hpp

* Cleaned up redundant code in unicode functions and iterators

* constexpr crazy

* Corrected includes