Allow batform to quaff potions and open doors

It was a fairly weird exception - all the other player bad-polymorph forms can
read and quaff, and even wisp/pig/porcupine could use doors. Also makes Vampire
batform a little better and less fiddly.

crawl-ref/source/dat/descript/ability.txt

@@ -61,7 +61,7 @@ Breathes a blast of noxious fumes at a targeted creature.
 Bat Form ability
 
 Transforms you into a swift-moving vampire bat. The user becomes unable to
-drink potions or evoke wands, to open or close doors, or to cast spells.
+evoke wands or to cast spells.
 %%%%
 Spit Acid ability
 

crawl-ref/source/item_use.cc

@@ -1896,13 +1896,6 @@ void drink(item_def* potion)
         return;
     }
 
-    if (you.form == TRAN_BAT)
-    {
-        canned_msg(MSG_PRESENT_FORM);
-        _vampire_corpse_help();
-        return;
-    }
-
     if (you.duration[DUR_NO_POTIONS])
     {
         mpr("You cannot drink potions in your current state!");

crawl-ref/source/main.cc

@@ -2848,14 +2848,6 @@ static void _open_door(coord_def move)
         return;
     }
 
-    // If we get here, the player either hasn't picked a direction yet,
-    // or the chosen direction actually contains a closed door.
-    if (!player_can_open_doors())
-    {
-        mpr("You can't open doors in your present form.");
-        return;
-    }
-
     if (you.confused())
     {
         canned_msg(MSG_TOO_CONFUSED);
@@ -2946,12 +2938,6 @@ static void _open_door(coord_def move)
 
 static void _close_door(coord_def move)
 {
-    if (!player_can_open_doors())
-    {
-        mpr("You can't close doors in your present form.");
-        return;
-    }
-
     if (you.attribute[ATTR_HELD])
     {
         mprf("You can't close doors while %s.", held_status());

crawl-ref/source/player.cc

@@ -601,11 +601,6 @@ bool player_likes_lava(bool permanently)
            && form_likes_lava();
 }
 
-bool player_can_open_doors()
-{
-    return you.form != TRAN_BAT;
-}
-
 /**
  * Is the player considered to be closely related, if not the same species, to
  * the given monster? (See mon-data.h for species/genus info.)

crawl-ref/source/player.h

@@ -1008,8 +1008,6 @@ void forget_map(bool rot = false);
 int get_exp_progress();
 void gain_exp(unsigned int exp_gained, unsigned int* actual_gain = nullptr);
 
-bool player_can_open_doors();
-
 void level_change(bool skip_attribute_increase = false);
 void adjust_level(int diff, bool just_xp = false);
 

crawl-ref/source/travel.cc

@@ -247,10 +247,6 @@ bool feat_is_traversable_now(dungeon_feature_type grid, bool try_fallback)
         // Permanently flying players can cross most hostile terrain.
         if (grid == DNGN_DEEP_WATER || grid == DNGN_LAVA)
             return you.permanent_flight();
-
-        // You can't open doors in bat form.
-        if (grid == DNGN_CLOSED_DOOR || grid == DNGN_RUNED_DOOR)
-            return player_can_open_doors();
     }
 
     return feat_is_traversable(grid, try_fallback);