widget_var for linking avatar attributes to widgets:
- focus, move, pain, speed, stamina, stats, HP per bodypart and more

widget class to render avatar variables in UI with labels and layout:
- uses generic_factory to load JSON from widget types
- JSON: id, label, style, var, colors, symbols, width, fill, etc.
- show() to render widget value from avatar instance
- layout() to arrange widgets and do max width padding/alignment
- get_var_value() to return avatar's current "var" value
- color_value_string() to render value with colors
- supporting: value_color(), value_string(), graph(), num()

Build on the data-driven sidebar `widget` class, defining a collection
of numeric and graph display elements, including familiar as well as new
informational displays:

- HP bar graphs for each body part, in familiar `|||||` form
- Classic and extended (10-character) stamina graph
- Numeric indicators for sound, focus, pain, moves, str, dex, int, per
- Encumbrance bar graphs for each body part
- Warmth numbers for each body part
- Hunger, thirst, and pain phrases

Add a "Data Drive Sidebar Demo" section that can be toggled on for each
sidebar layout (classic/labels and narrow/compact), loading from the
"root_layout" widget.

widget_var for linking avatar attributes to widgets:
- focus, move, pain, speed, stamina, stats, HP per bodypart and more

widget class to render avatar variables in UI with labels and layout:
- uses generic_factory to load JSON from widget types
- JSON: id, label, style, var, colors, symbols, width, fill, etc.
- show() to render widget value from avatar instance
- layout() to arrange widgets and do max width padding/alignment
- get_var_value() to return avatar's current "var" value
- color_value_string() to render value with colors
- supporting: value_color(), value_string(), graph(), num()

src/widget.cpp Use get_focus

pain, hunger, thirst, and fatigue descriptions now available to modular
widgets

Gives cleaner-looking results, especially when value is empty