I keep forgetting these goofy things need to be here.

Add concat.php drop-in.

Add composer support

By adding this file, it adds support for the popular php dependancy manager composer.

Fix syntax error

No more 'k'!

Fix PHP Notice

Checking only `! is_array()` causes a notice when the purpose of that code is to set an empty array if one doesn't already exist. Commit adds `isset` checks to prevent the notice.

Fixes #3

Fixes #1

Fix #2