'tips' fix and enhancement

When 'tips' are enabled, the farlook tip displays some text at the
start of getpos().  But it clobbered the initial prompt, leaving
the screen in an ambiguous state (seemingly a normal map display,
but it is actually waiting for player to move the cursor) after
removing the tip's popup window.

Reissue the prompt.  farlook's short but misleading prompt of
"Pick an object" is changed to "Pick a monster, object or location".
I would normally include a comma before "or" but omitting it makes
the longer text seem slightly less cluttered.

The other tips are all one-line, delivered via pline().  Prefix
all of their messages with "Tip:" (which the farlook one already
uses) as a hint for using OPTIONS=!tips to shut them off.

src/getpos.c

@@ -4,7 +4,7 @@
 
 #include "hack.h"
 
-extern const char what_is_an_unknown_object[]; /* from pager.c */
+extern const char what_is_a_location[]; /* from pager.c */
 
 staticfn void getpos_toggle_hilite_state(void);
 staticfn void getpos_getvalids_selection(struct selectionvar *,
@@ -265,7 +265,7 @@ getpos_help(boolean force, const char *goal)
         /* disgusting hack; the alternate selection characters work for any
            getpos call, but only matter for dowhatis (and doquickwhatis,
            also for dotherecmdmenu's simulated mouse) */
-        doing_what_is = (goal == what_is_an_unknown_object);
+        doing_what_is = (goal == what_is_a_location);
         if (doing_what_is) {
             Sprintf(kbuf, "'%s' or '%s' or '%s' or '%s'",
                     visctrl(gc.Cmd.spkeys[NHKF_GETPOS_PICK]),
@@ -816,7 +816,8 @@ getpos(coord *ccp, boolean force, const char *goal)
         mMoOdDxX[i] = gc.Cmd.spkeys[mMoOdDxX_def[i]];
     mMoOdDxX[SIZE(mMoOdDxX_def)] = '\0';
 
-    handle_tip(TIP_GETPOS);
+    if (handle_tip(TIP_GETPOS))
+        show_goal_msg = TRUE; /* tip has overwritten prompt in mesg window */
 
     if (!goal)
         goal = "desired location";