Change the logic of open line commands so that if a selection lies
on the end of line character of the line from which we open a new
line, that selection does not move.
If we have two clients, A and B, with B's cursor on the eol character
of line L, and A hits `o` while on line L, B's cursor should stay
on the same (logical) line. Previous behaviour would make B's cursor
jump on the newly inserted line.
Various places in Kakoune code used to modify selections so that
cursors would not lie on an end of line. Remove those to increase
Kakoune's consistency and simplicity.
Now that end of lines are highlighted separately, they should not
be handled specially in most commands.
The debug buffer is a bit special as lots of events might mutate it,
permitting it to be modified leads to some buggy behaviour:
For example, `pipe` uses a ForwardChangeTracker to track buffer
changes, but when applied on a debug buffer with the profile flag
on, each shell execution will trigger an additional modification
of the buffer while applying the changes, leading to an assertion
failing as changes might not be happening in a forward way anymore.
Trying to modify a debug buffer will now raise an error immediatly.
Move recording of keys to the input handler itself instead of the
Insert mode so that eventual nested modes (potentially introduced
by <a-;> will get their keys recorded as well).
Fixes#1680
That way, insert mode knows when it can restore selections/avoid eol
instead of (wrongly) doing it in the destructor that ends up running
unpredictibly (as the mode is kept alive during its on_key call, even
though it can happen that it is not the active mode anymore at the end
of that call).
Fixes#1580
There is no need to trigger that event on every keystroke, we can
trigger it only when we hit the idle timeout, avoiding computations
when input keys are pasted.
The solution is a bit hackish, as we only consider the 8th bit to
mean alt in normal mode, because its unlikely accentuated characters
are going to be mapped there. It fixes using Alt on xterm, and
probably on iterm2 as well (not requiring the meta-sends-esc config
change anymore)
