Given a list of words (strings), group consecutive words that start with the same letter (case-insensitive). Return a list of groups where each group is a list of the consecutive words sharing the same first character. Single words that don't share a starting letter with neighbors should be their own group.
(['Apple', 'apricot', 'Banana', 'berry', 'Cherry', 'citrus', 'date'])[['Apple', 'apricot'], ['Banana', 'berry'], ['Cherry', 'citrus'], ['date']]