Write unittests for dirrlicht.io

[danyalzia]

As of this wrtiting this, there is barely any unittest written for the dirrlicht.io module because of the following reasons:

• Some classes still aren't implemented.
• Unlike other modules, this one requires special use-cases such as testing whether reading from a valid xml or writing it works as expected.
• I didn't use this module in my past pet projects, so I SUCK.