/******************* Syntax  ***********************

Statement::
   MacroDefinition
 | PlotStatement   
 | ColorStatement
    
MacroDefinition::
   ConstantDefinition
 | FunctionDefinition

ConstantDefinition::
  [DEFINE] ConstantName = ExpressionC

FunctionDefinition::
  [DEFINE] FunctionName(IdentifierF [[IdentifierF]]) = ExpressionF

PlotStatement::
PLOT  ExpressionP, ExpressionP FOR ExpressionC < IdentifierP < ExpressionC

Expression_3::
    [+] Expression_2 [+ Expression_2]]

Expression_2::
    Expression_1 [[* Expression_1]]

Expression_1::
    Expression_0 [^ Expression_0]

Expression_0::
    Number
  | (Expression_3)
  | ConstantName
  | FunctionName(Expression_3 [[Expression_3]])
  | SIN(Expression_3)
  | Identifier

Atom:: IdentifierF | IdentifierP

ColorStatement::
     COLOR(color)
 | COLOR(Number,Number,Number)

---------------------------------

  After macro expansion  ExpressionC is an Expression_3 containing
  no Identifier,   ExpressionF is an Expression_3 containing only
  the IdentifierFs in the declaration, and ExpressionP is an
  Expression_3 containing only the IdentifierP after the FOR.
  color is one of the strings in colorList of class ColorStatement
  below (case insensitive)