* Handle preference fragments using the framework
The previous code started new preference "screens" as activities, even though
each one hosted a single fragment.
Modify this to use the framework's support for swapping in/out different
preference fragments.
PreferencesActivity:
- Remove the code for launching tab and proxy preferences
- Remove the code for setting titles, each fragment is responsible for that
- Implement OnPreferenceStartFragmentCallback to swap fragments in/out with
the correct animation
PreferencesFragment:
- Use `fragment` property instead of `setOnPreferenceClickListener`
- Set the activity title when resuming
Everything else:
- Set the activity title when resuming
* Implement HTTP proxy summary as a SummaryProvider
Uses the frameworks's support for setting summaries instead of rolling our
own.
Also fix a tiny bug -- the minimum port number to connect to should be 1,
not 0.
* Lint
* replace hard-coded strings with existing constants
* proxy port
* * custom proxy port and hostname inputs
* typesafety, refactor, linting, unit tests
* relocate ProxyConfiguration in app structure
* remove unused editTextPreference fn
* allow preference category to have no title
* refactor proxy prefs hierarchy/dependency
