Add basic editing to tui

tui_main.c

@@ -1,6 +1,7 @@
 #include "bank.h"
 #include "base.h"
 #include "field.h"
+#include "gbuffer.h"
 #include "mark.h"
 #include "sim.h"
 #include <getopt.h>
@@ -384,6 +385,11 @@ int main(int argc, char** argv) {
       break;
     }
 
+    if (key >= '!' && key <= '~') {
+      gbuffer_poke(field.buffer, field.height, field.width, tui_cursor.y,
+                   tui_cursor.x, (char)key);
+    }
+
     // ncurses gives us the special value KEY_RESIZE if the user didn't
     // actually type anything, but the terminal resized.
     // bool ignored_input = ch < CHAR_MIN || ch > CHAR_MAX || ch == KEY_RESIZE;