Sextants are similar to quadrants and should align with them and
other box drawing, thus use builtin font to align them properly.

Part-of: #7422.

Fixes #7470.

Iterate over points in line instead of drawing it right away
and then finding it in the buffer.

Fixes: 4a26667060 (Use builtin font to draw powerline symbols)

In addition to box drawing it was decided to also draw powerline
symbols, since those are quite common and rather simple to draw with
present box drawing infra.

After evaluation of the ahash with the data alacritty uses it was
discovered that it's 1.5-2x times faster when getting the already
hashed values, which is the primary cases for alacritty's renderer.

Given that ahash is generally faster, all the HashSet and HashMap's
inside the alacritty were changed to use it as a hasher function.

This fixes an issue with terminal resizes when the selection is on the
last line. Alacritty would fail to rotate lines and keep the selection
in the same line index whenever the terminal line count was grown or
shrunk.

This issue occurred due to the range passed to the selection's rotate
function still being based on the old terminal size, which caused the
initial or target state of the rotation to be outside of the terminal
bounds.

Closes #6698.

This fixes the regression introduced by 2d27fff.

Fixes #6688.