Standardize actors colors

[Clarkszw]

I have added a new function check_color_range() `normalize_color()' in utils.py for #458 It does two things:

1. check if the color array is in range [0, 1]
2. if not, it will change it to red color [1, 0, 0] and print the out of bounds information normalize the color array.

I have written an unit test for this function and added in test_utils.py

All tests in test_actors.py and test_utils.py are passed :)

[skoudoro]

also, can you solve the conflict in this PR ? thank you

[Clarkszw]

I have no idea why it will happen..But the conflict has been fixed now:)