The functions encode and decode are now capable of processing larger
buffers with less conditional logic. Input and output functions need to
follow suit to make better use of this next. Encode without line
wrapping already makes use of these improvements, because input and
output are now entirely handled by <stdio.h> functions.
This should've been part of 848c37, when buffers were unwired from input
functions. Now buffer size is also no longer supplied in function calls
but assumed. It is up to the caller to provide appropriately sized
buffers.
