Add a `continue` statement

[minhduc0711]

Describe the improvement you'd like Many programming languages support the keyword continue, which is used in a loop to skip the rest of the code and move to the next iteration immediately. I personally find this keyword very useful when the branching logic inside the looped code gets a bit complicated.

Describe alternatives you've considered I don't think that such a statement exists in GAMA yet.

Additional context I'm happy to open a pull request for this, and I'd appreciate it if anyone can give me some pointers on where to start.