less: reuse former vi's key reading code. Improve SIGWINCH handling.

function                                             old     new   delta
less_main                                           2056    2097     +41
getch_nowait                                         248     273     +25
read_key                                             310     321     +11
static.esccmds                                        61      69      +8
count_lines                                           72      74      +2
less_gets                                            166     142     -24
less_getch                                           172      43    -129
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(add/remove: 0/0 grow/shrink: 6/5 up/down: 91/-170)           Total: -79 bytes
   text    data     bss     dec     hex filename

4 files changed