Add local var methods to Binding

[mlarraz]

These are defined in MRI as of 2.1.

I basically just copied these from the RubyDocs.

My implementation of Binding#local_variable_set assumes obj responds to #to_s, which may cause issues.

[YorickPeterse]

No, we're not going to rely on eval for this. Instead we should use Rubinius::VariableScope to get/set any local variables in a scope. See

rubinius/kernel/common/eval.rb

Lines 109 to 112 in 7362475

	def local_variables
	scope = Rubinius::VariableScope.of_sender
	scope.local_variables
	end

as an example.

Also, if we have any tagged specs for this they'll need to be untagged, otherwise new specs should be added.

[mlarraz]

So my only question about using Rubinius::VariableScope is that the getter/setter methods only seem to consider dynamic locals. Is there an API to get/set locals from Rubinius::CompiledCode?

[YorickPeterse]

VariableScope puts eval'd variables under VariableScope#dynamic_locals. Looking at things we probably need to expose some extra bits to this class. There's VariableScope#set_local but this requires a slot number (= basically the position in the local variables list) instead of just a variable name.

[brixen]

Are there specs for this?

[YorickPeterse]

Don't think so, at least I can't find any in our repo.

[YorickPeterse]

Fixed in 40f04c1, thanks for initially looking into this.