Add get_line_range() to RichTextLabel

[markdibarry]

Describe the project you are working on

A dialog system.

Describe the problem or limitation you are having in your project

In my system the dialog is paged, so it requires knowledge of the index of the first and last character of each page. Currently, to get the range of a page, line, or otherwise requires looping through the entire string and calling get_character_line() for every char.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

This retrieves the first and last character index for each line, making it much faster and easier task to get the range of a page in my system.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Retrieves the visible character range of the line provided as a Vector2i.

If this enhancement will not be used often, can it be worked around with a few lines of script?

Yes. I can currently do this by looping through the entire string and calling get_character_line() for every character but for longer dialog scripts this can be inefficient.

Is there a reason why this should be core and not an add-on in the asset library?

RTL is core.