puzzles: refactor and resync with upstream

This brings puzzles up-to-date with upstream revision
2d333750272c3967cfd5cd3677572cddeaad5932, though certain changes made
by me, including cursor-only Untangle and some compilation fixes
remain. Upstream code has been moved to its separate subdirectory and
future syncs can be done by simply copying over the new sources.

Change-Id: Ia6506ca5f78c3627165ea6791d38db414ace0804

apps/plugins/puzzles/src/malloc.c

@@ -0,0 +1,53 @@
+/*
+ * malloc.c: safe wrappers around malloc, realloc, free, strdup
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "puzzles.h"
+
+/*
+ * smalloc should guarantee to return a useful pointer - Halibut
+ * can do nothing except die when it's out of memory anyway.
+ */
+void *smalloc(size_t size) {
+    void *p;
+    p = malloc(size);
+    if (!p)
+	fatal("out of memory");
+    return p;
+}
+
+/*
+ * sfree should guaranteeably deal gracefully with freeing NULL
+ */
+void sfree(void *p) {
+    if (p) {
+	free(p);
+    }
+}
+
+/*
+ * srealloc should guaranteeably be able to realloc NULL
+ */
+void *srealloc(void *p, size_t size) {
+    void *q;
+    if (p) {
+	q = realloc(p, size);
+    } else {
+	q = malloc(size);
+    }
+    if (!q)
+	fatal("out of memory");
+    return q;
+}
+
+/*
+ * dupstr is like strdup, but with the never-return-NULL property
+ * of smalloc (and also reliably defined in all environments :-)
+ */
+char *dupstr(const char *s) {
+    char *r = smalloc(1+strlen(s));
+    strcpy(r,s);
+    return r;
+}