Instauration of Asynchronous actions

What's new ?

• You can now define asynchronous actions into your signals in order to perform some asynchronous task like fetching data from a server or anything else and directly update the state with the value returned.
• You can now access to the updated state directly after calling an async action from a function and use it to do other tasks

Bug fixed

• You can now use GX in a Strict Mode without any problem.