Change default albedo to reflect more acccurate lake water conditions

[tadhg-moore]

The default albedo has very high estimations of albedo [0.3-0.6]. Adjusted so it takes a constant value [0.08], and this also allows for it to be a parameter to be included in calibration routines.

Albedo output from GOTM using the default method (1; Payne (1972) method).

[tadhg-moore]

Following discussion with @jorritmesman these ranges are due to the timestep and averaging GOTM output is saved at.

But I still thinking adjusting to a constant value is a better approach than leaving it at the default values and it being a parameter to adjust.