Dynamic section

Note: maps assigned in binding cannot be changed anymore

For instance, this does not work:

binding
 MapA=a.map;    # input map
 MapC=c.map;

areamap
 mask.map;

timer
 1 10 1;

initial
 MapB=5*MapA;
 MapA=MapB/10;         # this is NOT POSSIBLE

... rest of script below ...