Add an option to export the function table

[dcodeIO]

Adds an --exportTable option to export the function table to the host. Background: We are currently not exporting it by default (unlike memory) do allow Binaryen to "directize" indirect calls, which exporting the table prohibits since the table can be modified externally.

fixes #1000

[willemneal]

Perhaps mention that it will be at the top level namespace and the other imports are in the env namespace.

[dcodeIO]

Exports don't have namespaces, like imports, but I can mention that it becomes exported as table. Is that what you meant?

[willemneal]

I thought that you could do the following: @external("env", "foo")
So that the instance will have the namespace env. I didn't mean the typescript namespace, rather just instance.env.table and imports.env.table.

[dcodeIO]

Yeah, one can do that on imports, which have a module name and a name, but exports just have a name without nesting. As such, there's no exports.env.table by design, only our mangling like exports["env.table"] as the loader understands it.