Partly completed code for "playground mode", issue #52
Committing Andrei's code from his thesis to the Analysis project.
Incomplete code for rewriting code to perform tracing.  Lots of work
left to do:

* random inner blocks
* inheritance hierarchy for MyStatement class? (currently uses an enum
to track the type, which isn't very OO)
* loop counts and nested loop counters
* re-write vardecs with default value assignments, i.e. String str;
should be String str=null;
* re-write return statements
* don't instrument break or throw, at least for now
* not sure what to do with catch statements; ignore for now
* wrote this on my whiteboard: "vars created after start line of stmt
(for loop?) if even possible..."  Unsure what this means
Merge branch 'master' of github.com:daveho/CloudCoder
Refactor:  Moved TextDocument and ApplyChangeToTextDocument into the
model classes, since these are currently only used by the
analysis (research) code but might be used by the builder or by the
webapp.
Added code that parses a series of Changes into a LineEditSequence made
up of a sequence of LineEdits.  Basically we're reconstructing
more course-grained line-by-line edits from the finer-grained Change
events.
Prototype of the new "Playground Mode", where students can type in and
text arbitrary code that is not tied to a particular set of test
cases. So far this only supports Java (language selection doesn't work
yet) and the inputs cannot be changed.
Merge branch 'master' of github.com:cloudcoderdotorg/CloudCoder
Merging changes from trunk.
ignoring CloudCoderBuilder since it is pre-empted by CloudCoderBuilder2
Mostly functional version of 'Playground mode' Issue #52.  Still need to add support for additional languages, saving/loading of code state, changing the text input, and adding, or removing, new test cases with their own inputs.\nAlso refactored TestResultsListView to make multi-line output columns into a generic component.