keyboardwalk

• walk / walk_rec: given a keyboard and a string, is the string a walk of the keyboard?
• gen_rand_walk: given a keyboard, generate a keyboard walk / key boardwalk string

keyboard	walk	keyboardwalk?
lol	ok	no
qwertyuiop asdfghjkl zxcvbnm	wsdxcv	yes
qwertyuiop asdfghjkl zxcvbnm	qwertgbnji	yes
qwertyuiop asdfghjkl zxcvbnm	qwertybnm	no