The wording was a bit confusing and misled at least one person into
thinking it behaved like `str.replace('c', '')` operating on the entire
line. Tweak the wording to be more precise and avoid this confusion.
This is a side effect of requiring Python >= 3.7 which itself guarantees
dictionary order. This is now a Meson language guarantee as well which
is required for passing default_options as dict and is generally
expected by users.
The new splitlines method on str is intended to replace usage of
fs.read('whatever').strip().split('\n').
The problem with the .strip().split() approach is that it doesn't have a
way to represent empty lists (an empty string becomes a list with one
empty string, not an empty list), and it doesn't handle Windows-style
line endings.