fix issue #1305 - failed #untrap from doorway

Issue reported by loggersviii:  attempting #untrap from an adjacent
doorway can move the hero diagonally out of the doorway.

A followup comment by elunna pointed out that a monster's attack that
results in knockback can produce similar result.

Fixes #1305

src/hack.c

@@ -47,7 +47,6 @@ staticfn struct monst *monstinroom(struct permonst *, int) NONNULLARG1;
 staticfn boolean furniture_present(int, int);
 staticfn void move_update(boolean);
 staticfn int pickup_checks(void);
-staticfn boolean doorless_door(coordxy, coordxy);
 staticfn void maybe_wail(void);
 staticfn boolean water_turbulence(coordxy *, coordxy *);
 
@@ -963,7 +962,7 @@ invocation_pos(coordxy x, coordxy y)
                       && x == svi.inv_pos.x && y == svi.inv_pos.y);
 }
 
-/* return TRUE if (dx,dy) is an OK place to move;
+/* return TRUE if (ux+dx,ux+dy) is an OK place to move;
    mode is one of DO_MOVE, TEST_MOVE, TEST_TRAV, or TEST_TRAP */
 boolean
 test_move(
@@ -2749,20 +2748,8 @@ domove_core(void)
             || Hallucination)) {
         char qbuf[QBUFSZ];
         int traptype = (Hallucination ? rnd(TRAPNUM - 1) : (int) trap->ttyp);
-        boolean into = FALSE; /* "onto" the trap vs "into" */
+        boolean into = into_vs_onto(traptype);
 
-        switch (traptype) {
-        case BEAR_TRAP:
-        case PIT:
-        case SPIKED_PIT:
-        case HOLE:
-        case TELEP_TRAP:
-        case LEVEL_TELEP:
-        case MAGIC_PORTAL:
-        case WEB:
-            into = TRUE;
-            break;
-        }
         Snprintf(qbuf, sizeof qbuf, "Really %s %s that %s?",
                  u_locomotion("step"), into ? "into" : "onto",
                  defsyms[trap_to_defsym(traptype)].explanation);
@@ -3910,7 +3897,7 @@ lookaround(void)
 }
 
 /* check for a doorway which lacks its door (NODOOR or BROKEN) */
-staticfn boolean
+boolean
 doorless_door(coordxy x, coordxy y)
 {
     struct rm *lev_p = &levl[x][y];