lineedit: fix handling of repeating Alt-b, Alt-f, Alt-d, Alt-Backspace

lineedit: fix handling of repeating Alt-b, Alt-f, Alt-d, Alt-Backspace

These key combinations should repeat correctly when the keys are
pressed and held.

Before this change, they do this erratically - many repeats are "eaten"
because they are treated as unrecognized ESC seqs:
ESC 0x7f is treated by Alt+baskspace, but ESC 0x7f ESC 0x7f ESC 0x7f
is unrecognized.

Escape sequences corresponding to these key combinations are moved from
read_line_input to lineedit_read_key.

Also, these key sequences are now enabled regardless of whether
FEATURE_EDITING_VI is set, since Vim does not actually support these key
combinations, but they are present in readline library.

function                                             old     new   delta
static.esccmds                                        93     103     +10
read_line_input                                     3737    3687     -50

Signed-off-by: Rostislav Skudnov <rostislav@tuxera.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>