c51fc7bed6
buffer between commands, not recalculate its length all the time, and to not reallocate its fixed-length buffer frequently. fixed the 'c', 'd', and 'y' commands to properly handle both motions that are just part of a line, and those that are multiline. for instance, now "c%" and "2cw" work correctly, whether the motions span lines or not. added some permissble motions for 'c', 'd', and 'y': namely 'h', 'l', SPACE, BS, and DEL