Added security

No this isn't an invitation to attempt to attack the site of the company I work for (although if you find any vulnerabilities let me know NICELY!). I used the information in this article Writing Secure PHP to help me fix any bugs. Most of the fixes I did weren't major security issues but It was good to double check and I ended up making some things fail a little more pleasantly so that if someone tries to look for a page that isn't there they get a neat message rather than a PHP "file not found" or blank page.