add procedural calls to functional functions in levelbuilder mode.

In level builder, we want to be able to make a procedural call to a functional function. This is so that the levelbuilder can e.g. write a play lab game using procedural statements, which make a call to a functional function definition which is defined by the user such as safe-left, safe-right, safe-both. See the following levels for examples, which currently use procedural definitions that we want to replace with functional ones:
http://levelbuilder.code.org/s/msm/stage/14/puzzle/1
http://levelbuilder.code.org/s/msm/stage/14/puzzle/2
http://levelbuilder.code.org/s/msm/stage/14/puzzle/3

screenshot of this pull request in action:
![screen shot 2014-11-13 at 10 18 44 pm](https://cloud.githubusercontent.com/assets/8001765/5042045/3289b4ba-6b83-11e4-8715-440b9bd12fe0.png)

@bcjordan , @Bjvanminnen , please take a look when you get in.
Should this only be a subset of editBlocks? i.e. I suspect we don't want these for required_blocks/toolbox