Migrate to modular structure

[annybs]

Currently, all views are mixed together in a single views directory, and all components (including sub-views) in a single components directory.

This can make it difficult at times to perceive the component tree in a top-down view and lengthy component names compound the difficulty. Marginal difficulty, to be sure, but the codebase will continue to grow over time, so it will become increasingly helpful to properly compartmentalise various aspects of the app into clearly scoped modules, as we do in some other apps.

This will be a gradual effort introduced in the course of adding new features. Existing features can be scheduled for migration in the future.