Add a test program that dumps console input via _getch.

misc/GetCh.cc

@@ -0,0 +1,20 @@
+#include <conio.h>
+#include <ctype.h>
+#include <stdio.h>
+
+int main() {
+    printf("\nPress any keys -- Ctrl-D exits\n\n");
+
+    while (true) {
+        const int ch = getch();
+        printf("0x%x", ch);
+        if (isgraph(ch)) {
+            printf(" '%c'", ch);
+        }
+        printf("\n");
+        if (ch == 0x4) { // Ctrl-D
+            break;
+        }
+    }
+    return 0;
+}