Configuration as an app framework

[EmingK]

Currently reactor setup is a bunch of hand written windows that presents configuration editing.

Newly added apps will be highly probable use a similar configuration mechanism.

The configuration should be extracted to a framework to generate configuration UIs automatically and reduce boilerplate of writing new apps.

Proposed solution

• Add ConfigurableApp, providing a configSchema.
• A config schema describes all fields of config recursively, including field name, type, and how to handle presentation and editing.
• Port current implementation to be config schema based.