Add basic config file support to base station

[superdan-t]

This does not save keyboard or controller bindings, open windows, etc, but it makes using the base station easier. No scripting support either.

There is no default settings file. One is created to run in a userdata directory relative to the base station executable.

Closes #38

[superdan-t]

The most recent commit adds command line argument parsing.

You can use the options to configure the initial screen (dimensions, fullscreen mode, etc) or change the behavior for loading and saving settings (disable saving, supply a custom path, etc).

Additionally, you can override settings in the config file using positional arguments. The format is path.to.key=value.

Example:

basestation --no-save --settings ~/my_custom_settings.json network.subsystem_feed.enable=false

This example will launch the basestation with this configuration:

• Settings will not be saved upon exit
• Settings are loaded from a custom file ~/my_custom_settings.json
• The settings value network.subsystem_feed.enable is set to false, overriding whatever is in ~/my_custom_settings.json