FUNCTION:  Orbit - Orbit of a vector under the action of a Reflection group
    ,CALLING SEQUENCE:  Orbit(v,R);,    
PARAMETERS:  R = a root system data Structure
             v = a linear combination of e1,e2,...,SYNOPSIS:   
  A "vector" (distinct from the vector data Structure used by Maple) is a
  linear combination of the standard orthonormal basis e1,e2,e3,..., with
  coefficients that are rational or floating-point.
  If v is a vector, Orbit(v,R) returns a list consisting of all vectors u
  that can be obtained from W(R) acting on v by Reflections. If any
  floating-point coordinates occur in v or Base(R), then the result is only
  approximate in the sense that vectors u1 and u2 whose squared distance is
  at most epsilon ( = 0.001, by default) are considered to be equal. Also,
  vectors u such that Iprod(v0,u) <= epsilon are considered to not be on the
  positive side of the hyperplane orthogonal to v0.
  To adjust epsilon, assign a new value to Coxeter/default[epsilon].

  For a description of root system data Structures, see Coxeter[Structure].
EXAMPLES:   
  Orbit(e1+e2+e3,D3);       yields  [e1+e2+e3, e3-e1-e2, e2-e1-e3, e1-e2-e3]
  with(Weyl,Weights); w:=Weights(C4);
  Orbit(w[4],C4);           yields       [e4,e3,e2,e1,-e1,-e2,-e3,-e4],    
