notcurses_init: properly initialize rstate cursor

When we first begin operations, we need emit a cursor homing, which
we were not doing for the first line. As a result, the first row
didn't show up until you rendered something else, and even then
didn't show up unless you changed it (as it was otherwise undamaged).
This explains a lot of mystery behavior in notcurses-demo that I've
long told myself I'd hallucinated or imagined. Hurrah! but also
supershittytothemax! Thanks Marek Habersack for pointing out something
which led to an experiment which led to chasing this down once and
forever. Closes #619, w00t!

src/lib/notcurses.c

@@ -852,6 +852,7 @@ notcurses* notcurses_init(const notcurses_options* opts, FILE* outfp){
     free_plane(ret->top);
     goto err;
   }
+  ret->rstate.x = ret->rstate.y = -1;
   ret->suppress_banner = opts->suppress_banner;
   init_banner(ret);
   // flush on the switch to alternate screen, lest initial output be swept away

src/lib/render.c

@@ -347,7 +347,7 @@ paint(ncplane* p, cell* lastframe, struct crender* rvec,
         lock_in_highcontrast(targc, crender);
         cell* prevcell = &lastframe[fbcellidx(absy, lfdimx, absx)];
 /*if(cell_simple_p(targc)){
-fprintf(stderr, "WROTE %u [%c] to %d/%d (%d/%d)\n", targc->gcluster, prevcell->gcluster, y, x, absy, absx);
+fprintf(stderr, "WROTE %u [%c] to %d/%d (%d/%d)\n", targc->gcluster, targc->gcluster, y, x, absy, absx);
 }else{
 fprintf(stderr, "WROTE %u [%s] to %d/%d (%d/%d)\n", targc->gcluster, extended_gcluster(crender->p, targc), y, x, absy, absx);
 }*/
@@ -478,7 +478,7 @@ term_putc(FILE* out, const egcpool* e, const cell* c){
         return -1;
       }
     }else{
-// fprintf(stderr, "[%c]\n", c->gcluster);
+//fprintf(stderr, "[%c]\n", c->gcluster);
       if(ncfputc(c->gcluster, out) == EOF){
         return -1;
       }

src/poc/firstline.c

@@ -0,0 +1,26 @@
+#include <unistd.h>
+#include "notcurses/notcurses.h"
+
+int main(void){
+  struct notcurses_options nopts = {
+    .inhibit_alternate_screen = true,
+  };
+  struct notcurses* nc = notcurses_init(&nopts, NULL);
+  if(nc == NULL){
+    return EXIT_FAILURE;
+  }
+  if(ncplane_putstr_aligned(notcurses_stdplane(nc), 0, NCALIGN_CENTER,
+                            "Heute Die Welt, Morgens Das Sonnensystem!") <= 0){
+    notcurses_stop(nc);
+    return EXIT_FAILURE;
+  }
+  if(ncplane_putstr_aligned(notcurses_stdplane(nc), 2, NCALIGN_CENTER,
+                            "Heute Die Welt, Morgens Das Sonnensystem!") <= 0){
+    notcurses_stop(nc);
+    return EXIT_FAILURE;
+  }
+  notcurses_render(nc);
+  sleep(5);
+  notcurses_stop(nc);
+  return EXIT_SUCCESS;
+}