bugfix in scanner: reals were not treated correctly

module t
/*2.0
from m import :: T(C1)
0.2*/
//1.3
from m import T, C1
//3.1

will be transformed into

module t
/***/
from m import :: T(C1)
/***/
/*1.3
from m import T, C1
3.1*/

before scanning. In this way we achieve that the upper source can be
compiled with the 2.0 compiler as well as with the 1.3 compiler

The comments _must_ begin the line (no leading whitespaces are allowed).

character

function determinePriority added