- by moving Position into token, scanner dependencies
  are removed from several files
- clearer field names in token.Position, now possible to
  have a Pos() accessor w/o naming conflicts
- added Pos() accessor
- use anonymous token.Position field in AST nodes

R=r
DELTA=244  (28 added, 55 deleted, 161 changed)
OCL=26786
CL=26793