Improve Date.parse (#289)

* Improve `Date.parse()`

- rewrite `Date.parse()` with separate parsers
- return `NaN` for out of bounds field values as specified
- add `js_tzabbr` and `string_get_tzabbr` to handle timezone abbreviations
- improve `string_get_milliseconds` readability
- accept up to 9 decimals for millisecond fraction but truncate at 3
- accept many more alternative date/time formats
- add test cases in **tests/test_builtin.js**
- produce readable output for `Date` objects in repl 
- use `JSON.stringify` to output `Date` and `string` values in **repl.js**
- remove `String.prototype.__quote`
- add `minimum_length` macro to specify argument array sizes (C99 except MSVC)
- v8.js: parse all environment variables and output them, update **v8.txt**

cutils.h

@@ -108,6 +108,12 @@ static void *__builtin_frame_address(unsigned int level) {
 #define container_of(ptr, type, member) ((type *)((uint8_t *)(ptr) - offsetof(type, member)))
 #endif
 
+#if !defined(_MSC_VER) && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+#define minimum_length(n)  static n
+#else
+#define minimum_length(n)  n
+#endif
+
 typedef int BOOL;
 
 #ifndef FALSE