new unreachable code pruning; checks for missing strands/initially (the parser prevents
  these errors currently, but future language evolution may change that)

  Fix for bug 019 (allowing richer initializers for input globals).

  detabbing; some changes from vis12-cl branch

  merging some changes from the vis12-cl branch

  Fix for bug013; it is now a type error to declare non-value-type strand variables.

  Fixed bug018 (conflicts with C reserved words).  Also fixed issues for programs
  that do not define global or input variables.

  tab expansion

  Fix bug022 (empty sequence not supported yet)

  Fixed bug034 (issues with unused variable tracking)

  Added unused variable warnigns

  Working on unused variable warnings

  Starting to add support for detecting unused and shadowed variables.

  merging in changes from Lamont's branch.

  Working on support for empty sequences

  Fix for bug020 (updating of globals using the +=, etc. should not be allowed).

  Typecheck strand creation.

  code cleanup

  Fix issues in bug012.diderot.

  Removed obsolete comment

  Fix uncaught exception when attempting to match argument types.

  Minor cleanup

  Fix the handling of function parameters to allow them to shadow previous declarations (bug005).

  Add comprehensive checking for bad control flow to the typechecker.

  Add check that strands have at least one output variable.

  Fixed it so that type errors are no longer reported as uncaught exceptions.  Note that we
  still only handle one error at a time.

  Added function inliner to simplify phase.

  Bug fix: sequence dimensions are not limited to 1..3!

  Added parsing and typechecking support for user-defined functions

  when integer literals are promoted to real, convert the literals instead of
  putting a type coercion into the AST.

  Allow images as inputs

  fixed bug in typechecker

  Working on inputs

  Working on dynamic sequence loading

  Working on dynamic sequences

  Fix missing promotion cases

  Bug fixes for int to real promotion

  Implementing int -> real promotion

  Working on ":" support

  Added length function on dynamic sequences

  More work on dynamic sequences.

  Working on support for dynamic sequences; also adding support for type coercions.

  Create a branch to implement things that we need for the Vis 2012 paper

  Merging in changes from pure-cfg branch.

  Merging in changes from pure-cfg branch: removed CL, expanded trace, and added method name
  datatype.

  Added support for hest-based command-line arguments to trunk.  Also switched
  output filename to prog.txt (from mip.txt)

  Adding support for assignment operators to the trunk.

  more merging of pure-cfg changes back into trunk

  Backporting changes from pure-cfg branch.  These include the "actor" ==> "strand"
  changes.

  Changed typing rules for tensor construction.  The convention is now slow-to-fast
  for tensor dimensions.

  Upated URL in header to diderot-language.cs.uchicago.edu

  Bug fix: get the result type of condtional expressions right when simplifying

  Working on slice support

  Working on adding slice notation and fixed precedence of differentiation

  Added parse-tree support for conditional expressions (still need parser support)

  Bug fixes

  Made typechecking more strict.

  Cleanup and simplification of AST representation

  Adding simple-ast representation

  Restrict polymorphism to operators/functions.

  Split function and variable namespaces and add notion of restricted operations
  that cannot appear inside actor or initialization code.

  Added output state variables and stabilize methods

  Moving compiler sources into src/compiler

  Better error messages

  Code reorg and added type arguments to variable printing in ASTPP.

  Fixed some bugs in the basis

  Working on typechecker

  Working on typechecker

  Added new syntax for tensor-value construction and more work on typechecker.

  Working on typechecker

  More work on the typechecker

  Working on typechecker

  Working on typechecker

  Working on typechecker

  Propoagating changes to meta variables

  Working on typechecker

  Working on typechecker

  Working on typechecker

  Starting to write a typechecker