Fix multiline text drawing and height calculation

[FeeeeK]

Fixes #1646 .

Changes proposed in this pull request:

• Fixed size calculation and drawing of multiline text

Example

from PIL import Image, ImageDraw, ImageFont

font = ImageFont.truetype("tnr.ttf", size=80, encoding="unic")
text = "{{{{\n}}}}"

size = font.getsize_multiline(text)
print(size) # (152, 132) / (152, 168)
image = Image.new("RGB", size, color="#FFF")
draw = ImageDraw.Draw(image)
draw.multiline_text((0, 0), text, "#000", font)
image.save("a.png")

Then / Now

[FeeeeK]

Most tests fail because they are not designed to account for these changes, for example before the height of the blank line was equal to the height of A string, although font.getsize() returns (0, 0).
Most of the test images need to be changed to fix this.

[nulano]

So your proposal is to revert #1573? This will reintroduce the #1540 issue.

[FeeeeK]

Haven't seen this before. In this case, I don't know what can be done.