Implement common infrastructure for settings, account, and other data panels

[kenmanheimer]

Develop the infrastructure for implementing data panels which are defined by a combination of web-page html, delineating the panel layout and identifying the data details as special tag attributes, plus application code for fetching the data according to the html details and application code for handling form-submits that change the details that can be changed.

This will provide the basis for settings, account and file details, and so forth.

[kenmanheimer]

The infrastructure for including the settings in the UI (including footer, view, etc) is there. Plumbing is still needed for presenting and processing option settings, but the tab is occupied.

(Also, the footer is the wrong color in some renderings.)