feat(globals) Support exported global variables

[Hywan]

Fix #30

This PR introduces an Exported Global API. Usage is super simple:

instance = Wasmer::Instance.new bytes
x = instance.globals.x

assert x.mutable
assert_equal x.value, 7

x.value = 42

assert_equal x.value, 42

[ljulliar]

Hi Ivan,

Are you thinking of releasing the wasmer rubygem 0.3.1 with this new
feature for globals ?

Thanks!

[Hywan]

I want to wait for a last feature before releasing a new version. But if that's important for you, I can run a release before :-).

[ljulliar]

I can wait for some time. No problem.

…

On Mon, Feb 17, 2020 at 5:28 PM Ivan Enderlin ***@***.***> wrote: I want to wait for a last feature before releasing a new version. But if that's important for you, I can run a release before :-). — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#32>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAED4MFGPJKTXPMLKASFF3RDK3JFANCNFSM4KRNGBLQ> .

[Hywan]

@ljulliar 0.4.0 has been released, https://github.com/wasmerio/ruby-ext-wasm/releases/tag/0.4.0 🙂. Thanks for your patience.