fix: update display with handling

[Tieske]

Lua System changed the display width handling, see lunarmodules/luasystem#82.

So where this library currently keeps track of the history of validated widths, wrapping around the width functions in LuaSystem, we can now detect a single ambiguous width character, and reuse that across the board.

So the caches of the detected widths should be removed, and on startup/initialization we should test a single ambiguous width character, and store its width as a library global for all other width-checks to use.

This should simplify the implementation.

would require a minimum version of 0.7.0 of LuaSystem

[Gitkbc]

Submitted a refactor implementing the proposed simplification.

The new implementation:

• Removes per-character width caching
• Calibrates a single ambiguous-width character during initialization
• Delegates width handling to LuaSystem (>= 0.7.0)

PR: #206

Please let me know if any changes are required. Will be delighted to learn and work on it.

[Tieske]

@Gitkbc no need to comment here. Best to keep everything in one place; the PR. The issue is typically used to discuss possible solutions first (if the change warrants it). So once the PR is up, let's stick to discussing there.