String
========================

**Methods**

* String **toString()**:
   Returns the itself string

* String **ltrim()**:
   Trim non letters from left

* String **rtrim()**:
   Trim non letters from right

* String **trim()**:
   Trim non letters from both sides

* String **replace(String search, String replace)**:
   Replace part of the string and returns the new one

* String **substring(Int start, Int length)**:
   Retrieves a substring from the original one

* Bool **startsWith(String str)**:
   Returns true iff this String starts with the String given as argument

* Bool **endsWith(String str)**:
   Returns true iff this String ends with the String given as argument