[doc] Added some missing options (#5)

DropSymbols.
The scale option of the Normalize statement and MakeInteger.
When the second argument of mod_ is one, the function is left untouched.
Fixed #write and Delete Storage

The bugfix for fortran90 (or another one) had a bad sideeffect with
  #write " (%e)",expr
in that it forced a return after the %e and the ) came on a new line....
There were problems with Delete Storage. Not enough variables were
moved.