- cJSON library was added to thirdparty for json module
- json module added and json.parse() function implemented
- thirdparty library sources are directly imported
- io.readfile() function added
- less than function fix (wasn't returning boolean)
- min, max functions added
- map check values equal implemented
- check a string contains another with `in` keyword
- Number: isint, isbyte
- String: find, replace, split, startswith, endswith, strip
- Map: clear, has, get, pop
- list: insert, clear, find, pop
- removed str_sub builtin function as its redunent since we have
range slice over strings.
- moved lower, upper attributes of strings as methods
