Handle an array more judiciously

Explicitly establish the array, and then handle it differently,
depending on the number of elements within it.
Provided support for .txt suffixes

Maps the suffix to a request for a plain text version of a law. Per
#160.
Handle requests for a plain-text version of a law

Per #160.

I feel like this is messy. Too much logic in the view?
Finish render_plain_text

Moving from untested code to properly debugged code.
Fix a typo

Fixes `Notice: Undefined variable: url_suffix'
Merge pull request #208 from dtrebbien/patch-1

Fix a typo
Ignore the htdocs/xml/ folder
Remove closing PHP tags
Check that `$titles' is not empty
Remove unnecessary calls to isset()
Merge pull request #209 from dtrebbien/patch-3

Miscellaneous changes
Throw an exception if __autoload() fails

This gives a stack trace for tracking down where the class is used.
Protect against exploitation of CVE-2013-0249
Merge pull request #213 from dtrebbien/patch-2

Throw an exception if __autoload() fails
Remove Virginia-specific Tags code

I accidentally included some code that's being tested within the
Virginia implementation.
Merge pull request #214 from dtrebbien/patch-4

Protect against exploitation of CVE-2013-0249
Fix Notice: Undefined property: Structure::$structure
Fix a hard-coded path to 404.php
Merge pull request #217 from dtrebbien/patch-7

Fix Notice: Undefined property: Structure::$structure
Merge pull request #218 from dtrebbien/patch-8

Fix a hard-coded path to 404.php