convert: various conversion utilities

av

convert between characters and indices
e.g.   av 'abcde'

detab

remove tab stops
remove tabs from character string
left argument is tab width, default 4

hex

create verb for hex calculation
e.g. 'FF' + hex '8'

mfv

matrix from vector
[delimiter] mfv vector
default delimiter is ' '

quote

quote text
quote 'Pete''s Place'

vfm

vector from matrix
vector from matrix, lines separated by LF