Added mediawiki inter-site link syntax

- Added placeholder default content
- Added a clearCache function that is callable in console.log
- PageDown library now loaded via npm
- The “post/“ page path prefix is now configurable
- The Noddity root path defaults to the current path plus
“default-content/“
- Fixed a JS error caused when the “current” variable would sometimes
be undefined
- Default page is now index.md instead of home.md