Fix a bug where UnaryOp.toString() printed the open paren twice if it
was a paren op.
Create a way to scan tokens, augmented with the def/ref information for
identifiers.
Changes to support the error markers in the eclipse editor.
Working on incremental re-parsing
Got some working test cases with the incremental updater.
Add parser support for self-name on a function literal.
Move incremental updater into the desugar package.
Unary call as a suffix operator with empty parentheses.
New pass for the DefRefScanner to be used in the IDE>
Remove file range information from AST nodes so they can be edited more
easily.  Everything is almost working again, except the incremental
updater and one unit test for def/ref scanning.
Big refactor to handle source offsets relative to parents rather than
using absolute offsets, which should make incremenetal editing of the
parse trees more feasible.  Also change the meaning of a few operators,
particularly projection was simplified greatly in its desugaring.
Don't store a reference to the SourceExpr in the CoreExpr - we just need
the sourceLength.
Incremental updater is starting to work.  It's not as precise as it
could be, but it's compiling and running.
More tests passing.
Test cases are all passing now.