Create a custom character (gylph) for use on the LCD. Up to eight characters of 5x8 pixels are supported (numbered 1 to 8). The appearance of each custom character is specified by an array of eight bytes, one for each row. The five least significant bits of each byte determine the pixels in that row.
lcd: a variable of type serLCD
num: which character to create (1 to 8)
data: the character's pixel data