Enhance test system

- Tests are now named
- Testlogs are preserved between runs
- Tests can be run through Valgrind Memcheck tool

test/testdata/valid

@@ -1,67 +1,68 @@
+==== empty-string ====
 [""]
-========
+==== short-string ====
 ["a"]
-========
+==== simple-ascii-string ====
 ["abcdefghijklmnopqrstuvwxyz1234567890 "]
-========
+==== utf-8-string ====
 ["€þıœəßð some utf-8 ĸʒ×ŋµåäö𝄞"]
-========
+==== string-escapes ====
 ["\"\\\/\b\f\n\r\t"]
-========
+==== one-byte-utf-8 ====
 ["\u002c one-byte UTF-8"]
-========
+==== two-byte-utf-8 ====
 ["\u0123 two-byte UTF-8"]
-========
+==== three-byte-utf-8 ====
 ["\u0821 three-byte UTF-8"]
-========
+==== utf-surrogate-four-byte-encoding ====
 ["\uD834\uDD1E surrogate, four-byte UTF-8"]
-========
+==== escaped-utf-control-char ====
 ["\u0012 escaped control character"]
-========
+==== simple-int-0 ====
 [0]
-========
+==== simple-int-1 ====
 [1]
-========
+==== simple-int-123 ====
 [123]
-========
+==== negative-zero ====
 [-0]
-========
+==== negative-one ====
 [-1]
-========
+==== negative-int ====
 [-123]
-========
+==== simple-real ====
 [123.456789]
-========
+==== real-exponent ====
 [123e45]
-========
+==== real-capital-e ====
 [1E22]
-========
+==== real-positive-exponent ====
 [1e+2]
-========
+==== real-negative-exponent ====
 [1e-2]
-========
+==== real-capital-e-positive-exponent ====
 [1E+2]
-========
+==== real-capital-e-negative-exponent ====
 [1E-2]
-========
+==== real-fraction-exponent ====
 [123.456e78]
-========
+==== true ====
 [true]
-========
+==== false ====
 [false]
-========
+==== null ====
 [null]
-========
+==== empty-array ====
 []
-========
+==== empty-object-in-array ====
 [{}]
-========
+==== complex-array ====
 [1,2,3,4,
 "a", "b", "c",
 {"foo": "bar", "core": "dump"},
 true, false, true, true, null, false
 ]
-========
+==== empty-object ====
 {}
-========
+==== simple-object ====
 {"a":[]}