Adding support for double-precision.  The approach is to use typedefs in the C header
  files for the Diderot types.

  Added "-o" option to compiler.

  Split output code into two functions: one for nrrd files and one for text files.

Added the code for generating OpenCL

  Remove debugging output

  Working on support for parallel runtime

  Adding general support for command-line options

  Working on command-line options

  Working on command-line option support

  Working on multiple-target support

  Starting to work on supporting multiple targets

  Add framework to support command-line control of optimization

  Working on debugging value numbering

  Added check of image range type when loading images during simplify phase.  Also improved
  error message when either range or domain is incorrect.

  Hook in backtrace monitor

  IL pretty printers have been moved to top level

  Code reorganization: split the tree-il stuff into its own directory and moved the
  variable analysis into that directory too.  This reorg. is in anticipation of using
  the variable scoping information from VarAnalysis in the translation to TreeIL.

  A lot of changes to better handle variable scoping etc.

  Added timing of compiler phases to help isolate performance bugs.

  Debugging code generation

  Add codegen hook into driver

  Many changes to IL operators for fields and images.

  Creating a branch to explore a pure CFG IL

  Working on mid-to-low translation

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

  Slightly better error reporting

  Adding MidIL checking

  Added checking for HighIL representation

  Added HighIL to MidIL translation phase

  Working on debugging HighIL optimization

  Working on HighIL optimization

  Moving high-IL stuff to its own directory

  New version of IL with translation to HighIL and pretty printing.

  Use the log file for debugging output

  Added Inputs module to handle static input variables

  Working on translateion

  Added pretty printing for simplified AST

  Adding simplify pass to driver

  Moving compiler sources into src/compiler

  Added placeholder for pretty-printing AST after typechecking

  Working on typechecker

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

  Working on typechecker

  Working on typechecking for Diderot

  Fixing parser/scanner bugs

  Remove CM files

  New directory