Add a way to choose whether you want the procedures_defreturn block to have a statement stack

[mark-friedman]

The standard Blockly procedures_defreturn block has a statement stack. However, this plugin adds a "controls_do_then_return" block, as seen in here:

However, some users may not want to have to use that "controls_do_then_return" block and may want to use version that contains a statement stack.

[marktohark]

#28 (comment)

[TannerGabriel]

@mark-friedman Would you add an additional block with the Stack or change the current implementation?

[TannerGabriel]

Another option would be to enable or disable the stack inside of the mutation, similar to the allow statements field in the Blockly implementation.

[TannerGabriel]

I have created a draft PR with the prototype that I implemented last week. @mark-friedman, let me know if this is the implementation you thought about, or if there are any necessary changes.

[mark-friedman]

I have created a draft PR with the prototype that I implemented last week. @mark-friedman, let me know if this is the implementation you thought about, or if there are any necessary changes.

I'm not sure I remember exactly what I had in mind when I created this issue :-( but I think that your solution will work.