Fix out of bounds access in get_bar and improve satiety_bar

[Qrox]

Summary

SUMMARY: Bugfixes "Fix out of bounds access in get_bar and improve satiety_bar"

Purpose of change

Fix an out of bounds access in get_bar reported by AddressSanitizer, and improve satiety_bar.

Describe the solution

Stricter checks on the float and integer values.
Improve granularity of satiety_bar by using float instead of int, and update the unit test to match changed results.
Also use utf8_width instead of string::length, just in case the bar may contain some non-ascii character in the future.

Testing

Tested in game and hp bars / satiety bars were correctly displayed. Ran the satiety unit test and it passed.

[gkarfakis19]

I appreciate your help in improving satiety_bar, but I've got lots of changes planned for it over at #44562 and I think it'd be better if your changes were handled after my PR gets merged, as satiety bar has been refactored.

EDIT: If you prefer, you could commit your changes onto my PR and I would happily accept them, so this PR, which also improves the get_bar() functionality doesn't get blocked.

[Qrox]

Sure, I'll make a PR to your branch.

[ZhilkinSerg]

You can rebase your branch on top of latest master to avoid conflicts.

[ZhilkinSerg]

It fails to compile on gcc 5:

11:15:51 In file included from src/ui_manager.h:7:0,
11:15:51                  from src/output.cpp:37:
11:15:51 src/cuboid_rectangle.h: In instantiation of ‘struct rectangle<int>’:
11:15:51 src/output.cpp:1849:53:   recursively required by substitution of ‘template<class Point> Point clamp(const Point&, const inclusive_rectangle<Point>&) [with Point = int]’
11:15:51 src/output.cpp:1849:53:   required from here
11:15:51 src/cuboid_rectangle.h:9:37: error: ‘dimension’ is not a member of ‘int’
11:15:51      static_assert( Point::dimension == 2, "rectangle is for 2D points; use cuboid for 3D points" );
11:15:51                                      ^
11:15:51 cc1plus: error: unrecognized command line option ‘-Wno-unknown-warning-option’ [-Werror]

You probably should not use <int> here.

[Qrox]

I'm planning to address this in a different way at #44598. Disallowing using a valid syntax just to support an old compiler is too restrictive in my opinion.