Fixes for STRICT STANDARD errors in PHP 5.6

[mikeschinkel]

We are working on a project for WABE.org and are using PHP 5.6 and the plugin is throwing STRICT STANDARDS errors for a site that will launch Monday Sept 28th 2015. So I am providing a fix for those issues as well as fixing several other small issues I found, see below.

The fixes are not of the nature that are likely to break anything for existing sites; I avoiding making any backward incompatible changes.

Here is what this pull request includes:

• Fixes for STRICT STANDARD error through in PHP 5.6 when the signatures of methods in both parent and child classes do not match.
• Added class instance properties where they are obviously used but not declared.
• Added lots of PHPDoc to allow PhpStorm to error check the code.
• Used the correct constants for WordPress for require() statements, ones that do not assume the location of the plugin.
• Replaced calls to deprecated split() with calls to explode()
• Removed potentially problematic trailing ?> from nprml.php
• Cleaned up whitespace (ONLY because PhpStorm would not allow me to leave the whitespace as is.)

[mikeschinkel]

This PR is out of date and the later PR #32 addresses the critical fixes from this PR.