Add evaluators to debugger frames

[martinmcclure]

The user should be able to open evaluators in debugger frames. Code evaluated in this environment should have access to "self," named instance variables of self, and any other method temporaries that are available in the context.

In a block context, names defined in an outer context may not be easily resolved, but

• Should be resolved if those names were compiled into the block's VC
• Would be nice to be resolved if those names would have been available when the block was compiled, and the context in which those names are meaningful are still on the stack.
• Cannot be resolved if those variables are not in the VC and the context in which they are meaningful are no longer on the stack.