Create config system

[nyxxxie]

It would be cool to have a config library that allows us to get user defined values to use in program features. Implement a class in core that provides an API to do this, and saves/loads values from a yaml settings file. Default config file values should be stored in code somehow, preferably defined inside of modules that make use of them (for example, register config variables inside of hexeditor.py if any of them relate directly to it). Saved yaml files should override these default values.

[nyxxxie]

Check out https://github.com/google/python-gflags for an idea of what it would look like (only replace the whole FLAG thing with CONFIG or whatever)!