Hotkeys to change city detail tabs in cityview

**Issue by [RealAntithesis](https://github.com/RealAntithesis)**
_Sunday Nov 06, 2016 at 03:10 GMT_
_Originally opened as https://github.com/CQUI-Org/cqui/issues/47_

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Proposed enhancement to the city screen: hotkeys to switch the various views as follows:
1. Q and E: switch from food, amenities and housing <-> building/wonders <-> pantheon/religion information panels;
2. A and D: switch from production <-> gold purchase <-> faith purchase panels;
3. W and S: cycle between the cities (I actually missed those buttons on either side of the city name to cycle cities until today - they are not obvious at all, and just look like window dressing).

No files, tests, or code entry points are named. Start by locating the city screen (cityview) and its existing panel and city-navigation input handling, then verify the proposed Q/E, A/D, and W/S mappings in each relevant view; done means all listed panels and cities can be cycled with those hotkeys.

Written by the indexing model from the issue text.