Calls GA code from wall_follow
# Fixed 'Conditional jump or move depends on uninitialised value(s)' errors
# Replaced quick sort with bubble sort
# Gave the functions, called in ga(), more intuitive names
# Separate function for fitness calculation
# Retains randomly the best proportions of the old & new populations
# Added the 3 tutorial worksheets
# TODO: Need to check comments & call wall_follow from calFitness