TinyLang based on Lox lang

Dart implementation of Tiny lang Compile with dart2native main.dart -o bin/dlox.

Implementations changes:

• Use print and println functions instead of print statements
• Added native functions str and num for variable type casting
• Use let instead of var for variable declarations.
• Added break support
• Added support for native array with call to Array() : let array = Array();
• Added support for lambda functions with syntax fun (arg) {}
• Added native function exit(code) to exit program
• Added native function error(errorMessage) to display an error message to stderr
• Added native function throw(errorInstance) to display an error message and exit program
• Added support for ternary operator (?:)
• Use construct instead of init as class constructor
• Use : instead of < for class inheritance
• Added support for static methods with keyword static
• Added support for class getter method
• Added modular programs support through modules importing with keyword import
• Added standard library implemented in a mix of TinyLang and Dart with error classes (Error and RuntimeError classes), support for basic Math operations (Math class), basic collections (List and Map classes), basic file I/0 (File, Stat and Directory classes), basic string manipulations (String class) and basic I/O (Stdin, Stdout and Repl classes)