Add should keyword

[Bellisario]

Adds should keyword.

About (same added to README.md)

should

should can be used as an expression.
This keyword is useful if you want to prevent a function call (also async) to throw an error because you don't need to have any result and the real execution is just optional (so runs if supported).

should hello()

Is the same as:

try {
    hello();
} catch (e) {};

Warning: this feature can be helpful but also dangerous especially if you're debugging your application. In fact, this is made to be used as an optional function call (ex. should load content, but not necessary and knowing this feature is optional), if you call a function in this way while debugging, no error will be printed and the application will contine run as nothing happened.

[coderaiser]

Nice :)!