Working on printing support.

  Added typechecking support for sequences and for evals and evecs.

  Renamed the MethodName module StrandUtil and added the strand properties to it.  Also added
  strand properties to the IL representation.

  Added datatype to represent method names.

  Added clamp and assignment operators.

  Push input descriptor string through compiler phases.

  Changed syntax of input variables to require literal definitions and to
  allow a description string.

  Added standard method names to BasisNames module

  Change syntax for field probing.

  Added check for variable redefinition in the same scope

  Some debugging and added "^" as power operator.

  Adding support for zeros[shape] and changed I to identity[d]

  Generalized dot product to inner product of tensor types.  Added IL support for
  vector-matrix, matrix-vector, and matrix-matrix multiplications.  Code generation
  and runtime support is still missing.

  Adding support for infix dot and cross-product operators

  Added identity matrix support (still needs codegen support)

  Allow for overloaded functions (like lerp)

  Added TODO list to typechecker.sml

  Working on support for sequences

  Add stabilize method for strands that don't have them

  Fixed a typechecking issue with iteration

  Change "actor" to "strand"

  Creating a branch to explore a pure CFG IL

  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 fix: get the order of instantiated meta variables right

  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

  Move env.sml to env directory

  Propoagating changes to meta variables

  Working on typechecker

  Working on typechecker

  Working on typechecker

  Starting to write a typechecker

  Added intialization syntax