sixel: deepclean on any draw

Whether a draw is due to a move or a simple invalidation,
we need to go ahead and apply any outstanding deepclean to
the sixel beforehand. This eliminates the last bit of
flicker in the intro demo, at the orca's first location.
Also, never emit a '-$' sequence when deepcleaning a sixel.
Closes #1574. Closes #1568.

src/lib/sixel.c

@@ -654,7 +654,7 @@ deepclean_stream(sprixel* s, FILE* fp){
         y += 6;
         x = 0;
         state = SIXEL_WANT_HASH;
-        needclosure = needclosure | printed;
+        needclosure = 0;
         fputc('-', fp);
       }else if(c == '$'){
         x = 0;
@@ -704,6 +704,14 @@ err:
 
 int sixel_draw(const notcurses* n, const ncpile* p, sprixel* s, FILE* out){
   (void)n;
+  // if we've wiped any cells, we need actually wipe them out now, or else
+  // we'll get flicker when we move to the new location
+  if(s->wipes_outstanding){
+    if(sixel_deepclean(s)){
+      return -1;
+    }
+    s->wipes_outstanding = false;
+  }
   if(s->invalidated == SPRIXEL_MOVED){
     for(int yy = s->movedfromy ; yy < s->movedfromy + s->dimy && yy < p->dimy ; ++yy){
       for(int xx = s->movedfromx ; xx < s->movedfromx + s->dimx && xx < p->dimx ; ++xx){
@@ -713,14 +721,6 @@ int sixel_draw(const notcurses* n, const ncpile* p, sprixel* s, FILE* out){
         }
       }
     }
-    // if we've wiped any cells, we need actually wipe them out now, or else
-    // we'll get flicker when we move to the new location
-    if(s->wipes_outstanding){
-      if(sixel_deepclean(s)){
-        return -1;
-      }
-      s->wipes_outstanding = false;
-    }
     s->invalidated = SPRIXEL_INVALIDATED;
   }else{
     if(fwrite(s->glyph, s->glyphlen, 1, out) != 1){