Everything is better in color.
Added coloredEcho function that takes a message and a color.
echo(str) is now shortcut for coloredEcho(str, 0xffffffff) - printing in white.
Colors in model (which in theory shouldn't depend on SFML) are unsigned.
In view (which MUST depend on SFML for creating data to draw) they are sf::Color.
Default coloring is now:
echo in Lua - white.
Hints - green.
User code lines - yellow.
Error messages - red.