Use <pre> for log and solver output

[ojdo]

Just a suggestion: for consistency with the terminal usage, a fixed-width font would preserve any ascii-art or simply formatted tabular output within the solver output. I heavily make use of that for simple text tables, e.g.:

printf{t in time}:
    "%2i:\t%6g\t%6g\t%5g | %5g\t%5g\t%5g\n", 
    t, demand[t], supply[t], electricity_price[t], 
    storage_level[t], energy_purchase[t], energy_sold[t];

[cocoto]

Good idea, thank you for your contribution