Enhancement in MatrixField Matvec method

[shishiousan]

"scale" value is not be reflected when the "addContribution" is false in Matvec

The issue occurred in the following code

CALL tanmat%Matvec( &
    & x=sol, &
    & y=rhs, &
    & addContribution=.FALSE., &
    & scale=-dt)

I expected the above code yields the result such that $y = -dt*tanmat*sol$,
but it returned

y = tanmat * sol

without scaling by $-dt$.