refactor(sign): move legacy signs to extmarks

Problem:  The legacy signlist data structures and associated functions are
          redundant since the introduction of extmark signs.
Solution: Store signs defined through the legacy commands in a hashmap, placed
          signs in the extmark tree. Replace signlist associated functions.

Usage of the legacy sign commands should yield no change in behavior with the
exception of:
  - "orphaned signs" are now always removed when the line it is placed on is
    deleted. This used to depend on the value of 'signcolumn'.
  - It is no longer possible to place multiple signs with the same identifier
    in a single group on multiple lines. This will now move the sign instead.

Moreover, both signs placed through the legacy sign commands and through
|nvim_buf_set_extmark()|:
  - Will show up in both |sign-place| and |nvim_buf_get_extmarks()|.
  - Are displayed by increasing sign identifier, left to right.
    Extmark signs used to be ordered decreasingly as opposed to legacy signs.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 29f1cb2470..dbcb16cae3 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -2558,7 +2558,7 @@ void win_draw_end(win_T *wp, int c1, int c2, bool draw_margin, int row, int endr
     // draw the sign column
     int count = wp->w_scwidth;
     if (count > 0) {
-      n = win_fill_end(wp, ' ', ' ', n, win_signcol_width(wp) * count, row,
+      n = win_fill_end(wp, ' ', ' ', n, SIGN_WIDTH * count, row,
                        endrow, win_hl_attr(wp, HLF_SC));
     }
     // draw the number column
@@ -2633,7 +2633,7 @@ int number_width(win_T *wp)
 
   // If 'signcolumn' is set to 'number' and there is a sign to display, then
   // the minimal width for the number column is 2.
-  if (n < 2 && (wp->w_buffer->b_signlist != NULL)
+  if (n < 2 && wp->w_buffer->b_signs_with_text
       && (*wp->w_p_scl == 'n' && *(wp->w_p_scl + 1) == 'u')) {
     n = 2;
   }