Compiling with gfortran -- add space after STOP

[Beliavsky]

For the line

    stop("regex_test error: number of arguments should be exactly 2 or 3!")

in regex_test.f90 and

    if (classend.eq.0) stop("No terminating char class")

in fexp.f90

there should be space after stop. You can also remove the parentheses.