Separate local configuration

[mDuo13]

Certain config options are meant to be local to an individual system, not to a project, but they're all defined in the same config file. This doesn't really make sense for a shared project that stores the config file in version control.

System-local config options should be configurable from a separate file that's stored in a userspace location such as $HOME/.config/dactyl/local.yml or something. Such options include:

• temporary_files_path
• prince_executable

[mDuo13]

Modular config files in the repo level might also be useful. Could probably use https://github.com/tanbro/pyyaml-include to do that.