It is confusing to get header lines, hunk headers, or context lines rendered as
being included in a custom patch, when including these makes no difference to
the patch.
This is only a visual change; internally, we still record these non-patch lines
as being included in the patch. It doesn't matter though; you can press space on
a header line and nothing happens.
It would probably be cleaner to only record + and - lines in the includedLines
array, but that would be a bit more work, and doesn't seem worth it.
We're not fully standardising here: different contexts can store their range state however
they like. What we are standardising on is that now the view is always responsible for
highlighting the selected lines, meaning the context/controller needs to tell the view
where the range start is.
Two convenient benefits from this change:
1) we no longer need bespoke code in integration tests for asserting on selected lines because
we can just ask the view
2) line selection in staging/patch-building/merge-conflicts views now look the same as in
list views i.e. the highlight applies to the whole line (including trailing space)
I also noticed a bug with merge conflicts not rendering the selection on focus though I suspect
it wasn't a bug with any real consequences when the view wasn't displaying the selection.
I'm going to scrap the selectedRangeBgColor config and just let it use the single line
background color. Hopefully nobody cares, but there's really no need for an extra config.
