Newpagetemplate plugin support included

This PR adds support for the [newpagetemplate plugin](https://www.dokuwiki.org/plugin:newpagetemplate).
Also some reformatting and refactoring is done.

Handled syntax options: 
  *  `{{NEWPAGE}}` -- no options
  *  `{{NEWPAGE>your:namespace}}` -- define namespace
  *  `{{NEWPAGE#newtpl}}` -- define pagetemplate, added as hidden field
  *  `{{NEWPAGE#newtpl1,newtpl2}}` -- define more pagetemplates, shown as select
  *  `{{NEWPAGE#newtpl1|Title1,newtpl2|Title1}}`  -- define more pagetemplates, as select with nice titels
  * `{{NEWPAGE>your:namespace#newtpl1|Title1,newtpl2|Title1}}` -- all syntax combined