Paragraph doesn't calculate newlines and character positions correctly with ligatures enabled

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## Description of bug / unexpected behavior
When using a Paragraph with text with ligatures and newlines, character positions are wrong.

## Expected behavior

Characters should get rendered correctly, as they do without ligatures.

## How to reproduce the issue

Code for reproducing the problem

```py
class Example(Scene):
def construct(self):
# The font must have ligatures that apply to the character sequences in the text, of course.
# Most fonts have 'fi' and 'tt' ligatures though.
wrong = Paragraph(
'ffifififi\nfififitt tttfj', disable_ligatures=False, alignment='center', font='Candara', weight=LIGHT).shift(UP*2)
right = Paragraph(
'ffifififi\nfififitt tttfj', disable_ligatures=True, alignment='center', font='Candara', weight=LIGHT).shift(DOWN*2)
self.add(wrong, right)
```

## Additional media files

Images/GIFs


Start with the Paragraph usage in the Example.construct reproduction and compare the ligatures-enabled and disabled cases, especially across the newline. Trace how Paragraph calculates character positions for the shown text. Done means the ligatures-enabled rendering matches the disabled case for character placement and line breaks.

Written by the indexing model from the issue text.