dict: Raise MAX_DICT_HASH limit

This fixes quadratic behavior with large dictionaries.

Also rework testdict.c to support tests with larger dictionaries.
diff --git a/dict.c b/dict.c
index d7fd1a0..67b2a2e 100644
--- a/dict.c
+++ b/dict.c
@@ -62,7 +62,7 @@
 
 #define MAX_HASH_LEN 3
 #define MIN_DICT_SIZE 128
-#define MAX_DICT_HASH 8 * 2048
+#define MAX_DICT_HASH 100000000
 #define WITH_BIG_KEY
 
 #ifdef WITH_BIG_KEY
@@ -656,7 +656,7 @@
 	return(-1);
     if (size < 8)
         return(-1);
-    if (size > 8 * 2048)
+    if (size > MAX_DICT_HASH)
 	return(-1);
 
 #ifdef DICT_DEBUG_PATTERNS