Add export functionality for dictionary blocks

[meganindya]

I would've wanted a object key addition/object key query syntax, however, at the moment we have to go with method calls. I'll implement that.

[walterbender]

So far it looks good. What else are you planning? (As it is marked DRAFT.)

[meganindya]

I just separated the actions code from DictBlocks.js to DictActions.js. Now I got to implement the export API ... would end up with three methods showDict, setValue, and getValue

[walterbender]

I was going to add a pie menu for the dictionary keys with the getValue block in the dictionary, but I realized that there is no way to know what turtle is associated with the block when you click on it. So we cannot know how to populate the pie menu. Bummer.

[meganindya]

I got stuck too for a similar reason. turtleDicts and turtleHeaps are implemented as dictionaries with Turtle indices in turtleList as keys. It conflicts with having the Turtle object. For the same reason, I moved all other block properties from logo to Singer/Painter.

But, turtleHeaps was more convoluted so that wasn't done. Now, it's the same with turtleDicts too. If you ask me, I think we could move these into individual Turtle objects, but that has one problem — we wouldn't be able to share dictionaries/heaps between different start blocks.

I think we need a different implementation for these entirely.

[walterbender]

@meganindya Is this ready to test/review?

[meganindya]

I thought this was done. Very sorry :p

[meganindya]

Here's a working example:

[meganindya]

methods added:

setValue(key, value)                       set value to unnamed dictionary
setValue(key, value, dictionary)  set value to named dictionary
getValue(key)                                  get value from unnamed dictionary
getValue(key, dictionary)              get value from named dictionary
getDict(dictionary)                        get a dictionary
showDict(dictionary)                      print a dictionary (on top)

[meganindya]

BTW, we aren't being able to share dictionaries between turtles as of now. I think being able to do that would be really powerful e.g. being able to use actions as parameterized functions with the arguments being in some dictionary.

[meganindya]

closes #2587.

[walterbender]

Sharing between turtles was a big reason I refactored Christopher's original PR. I'd like to push the whole idea further at some point. Thx for the PR in any case.