Glitch-this

* Change `==` to `is`

*Thanks to [amancevice](https://github.com/amancevice) and [KopfKrieg](https://github.com/KopfKrieg)*

* Add detailed exceptions

*Thanks to [amancevice](https://github.com/amancevice)*

* Fix not being able to use image names with dots in them

*Thanks to [ojensen5115](https://github.com/ojensen5115)*

* Make `color_offset` optional, you can set it to `True` when calling `glitch_image()` or, if you're using the script, include the param `-c`.

* Base setup