Reverse order of comments

Closes #182 Added options to reverse order of comments and put the input form above comments, instead of below. As most of the time I expect either both or none of them to be used, they are handled by a common checkbox in the config generator. Overall it seems to work, but I have not tested it on cases with hidden pages (I have not seen any). Example config (from the `configuration-component`): ```html <script src="https://utteranc.es/client.js" repo="[ENTER REPO HERE]" issue-term="pathname" theme="github-light" reverse-order="true" input-position-top="true" crossorigin="anonymous" async> </script> ```