Allow setting color with an int from rainbowio

[Neradoc]

This makes it easier to use with rainbowio.

import time
import board
from rainbowio import colorwheel
import adafruit_character_lcd.character_lcd_rgb_i2c as character_lcd

# Modify this if you have a different sized Character LCD
lcd_columns = 16
lcd_rows = 2
# Initialize I2C bus.
i2c = board.I2C()
# Initialize the LCD class
lcd = character_lcd.Character_LCD_RGB_I2C(i2c, lcd_columns, lcd_rows)

lcd.clear()
# Print two line message
lcd.message = "Hello\nCircuitPython"
# Set LCD color
lcd.color = colorwheel(32)
time.sleep(1)

[dhalbert]

lgtm - thanks!