Add support for Variable declarations (let)

[gcanti]

Example

let bar: bool = foo;

bar = true;

compiles to

let bar = _assert(foo, _t.Boolean, "bar");

bar = _assert(true, _t.Boolean, "bar");

@christophehurpeau let me know if you want to work on this. From my part I'd love to help you out writing a test suite which I'll post later here or in a apposite branch

[christophehurpeau]

bar = true; should not compile to bar = _assert(true, _t.Boolean, "bar"); because we know that true is a boolean, in my opinion.

[gcanti]

Yeah, but seems just an optimization which btw implies a bit of (albeit basic) static analysis, I think it doesn't worth it to complicate the plugin code for this. In the end of the day asserts will be discarded in production builds

[christophehurpeau]

see #111

[ArmorDarks]

Hi!

It's slightly unclear — plugin still does not support lets?