Add NephroWiki.Plasma.js
Define resource module for Plasma calculator.
Add method to parse form fields.
Add calculation wrapper method to NephroWiki object.
Remove NephroWiki.Plasma.js.

Made a design decision to store calculation code directly with the form HTML
in the Wiki page, obviating the need to fiddle with JavaScript files on the
server at all.
Hand over the form params to the calculator function.
Add error handling.
Add error message for empty fields.
Implement slider width and span alignment.