Some JSHint fixes

Handled code issues:
* Converted ~~all~~ `==` and `!=` to `===` and `!==`.
* Removed unused variables (excluding parameters and `isPro`, `isDev` & `isDbg`).
* Removed unnecessary semicolons.
* Added missing semicolons.
* Fixed some issues where wrong variable names were used.
  * #267 at https://github.com/OpenUserJs/OpenUserJS.org/commit/82dc007493f122f619682d8ab5fc37948f90ffaa#diff-590bb4d75f87edbecb61fa8487493291L123
* Renamed already defined variable/function.

Not handled:
* Unused parameter variables.
* Lots of unused variables `isPro`, `isDev` & `isDbg`. +/-90% of the files have one these unused variables…
* `User.edit` still contains a lot of bugs, but this function is never used.
* Empty code blocks.
* Indentation
* Whitespace

No functionality should have been changed!

Node modules are ignored.

Ref https://github.com/OpenUserJs/OpenUserJS.org/pull/406

A change to get the code to a higher level of quality and consistency.

`linkedPages` is filled with Numbers as mentioned in the logic above where it's defined, initialized and filled up.