The pipe command can contain almost all printable characters. In
particular, we can expect it to contain '='.
Having the pipe command as part of the key breaks the key/value
splitting.
Change it so that it is instead an optional initial part of the value,
enclosed in '[]'.
I.e. instead of
pipe-visible:cmd=binding
we now need to write
pipe-visible=[cmd] binding
A key binding may now have an optional ':<cmd>' string appended to the
key.
This is intended to be used like so:
pipe-scrollback:sh -c "cat > file"=Print
TODO: we still only allow one *action*. Meaning you still cannot
specify multiple pipe-scrollback bindings, for example.
This allows us to safely call extract_finish() when extract_one()
failed, and we'll get the expected result; false, indicating
extract_finish() failed.
As that breaks e.g. selection marking (SPACER cells didn't get
inverted when rendered).
Instead, skip them in extract_one() only. I.e. when copying text from
the grid.
Ignore *old* cells containing spacers.
Pad new grid with spacers if a multi-column character doesn't fit at
the end of a line.
Insert spacers after a multi-column character.
When printing a multi-column character, write CELL_MULT_COL_SPACER
instead of '0' to both padding cells (when character doesn't fit at
the end of the line), and to the cells following the actual character.
When printing a multi-column character at the end of the line, and it
doesn't fit, we currently insert a forced line-wrap. This means the
last character(s) on the previous line will be empty, followed by a
multi-column character in the first cell on the next line.
Without special code to handle this, the selection text extraction
code will insert a hard newline, since this is normally the correct
thing to do.
Add a TODO, to consider writing a special place holder value to these
padding cells.
While this might seem like it would slow down things, it should in
fact help the compiler optimize: the "normal" code path, that prints
regular ASCII characters, always call term_print() with width == 1.
LF should always clear LCF. Previously, it was done implicitly in
term_cursor_down(). I.e it was cleared as long as the cursor wasn't at
the bottom of the scrolling region
