Fixed two bugs in subroutine glissade_calcbmlt

(1) Sometimes bflx was computed to be very slightly difference from zero, resulting
    in a very slightly negative value of bmlt, which triggers an erroneous drop of 0.01 deg
    in the temperature at the bed.  With the fix, bflux is set to zero if the computed
    magnitude is less than 1.d-11 W/m^2.

(2) The call to glissade_calcpmpt had incorrect vertical indexing, resulting in incorrect
    values for the pressure melting point temperature in the column.  The indexing is now correct.

Both bug fixes are answer-changing in problems with an evolving temperature field,
including EISMINT-2.
Added 'parameter' to the declaration of eps11 in glissade_calcbmlt.
Merge bugfix/v2.0.4: bmlt fixes

* piscees/bugfix/v2.0.4:
  Added 'parameter' to the declaration of eps11 in glissade_calcbmlt.
  Fixed two bugs in subroutine glissade_calcbmlt