Make the texture stuff completely integer-based again, but expose R_TextureNumForName

Decided that being able to set a string and then have it return an integer when retrieving would ultimately be confusing, so let's just let the user handle the string functions.

src/lua_baselib.c

@@ -1722,7 +1722,23 @@ static int lib_rSetPlayerSkin(lua_State *L)
 // R_DATA
 ////////////
 
-// This also doesn't exist, but we need it for texture find+replace to not be a horrible chore.
+static int lib_rCheckTextureNumForName(lua_State *L)
+{
+	const char *name = luaL_checkstring(L, 1);
+	//HUDSAFE
+	lua_pushinteger(L, R_CheckTextureNumForName(name));
+	return 1;
+}
+
+static int lib_rTextureNumForName(lua_State *L)
+{
+	const char *name = luaL_checkstring(L, 1);
+	//HUDSAFE
+	lua_pushinteger(L, R_TextureNumForName(name));
+	return 1;
+}
+
+// This doesn't exist, but we need it for texture find+replace to not be a horrible chore.
 static int lib_rGetTextureName(lua_State *L)
 {
 	INT32 texnum = luaL_checkinteger(L, 1);
@@ -2585,6 +2601,8 @@ static luaL_Reg lib[] = {
 	{"R_SetPlayerSkin",lib_rSetPlayerSkin},
 
 	// r_data
+	{"R_CheckTextureNumForName",lib_rCheckTextureNumForName),
+	{"R_TextureNumForName",lib_rTextureNumForName),
 	{"R_GetTextureName",lib_rGetTextureName},
 
 	// s_sound

src/lua_maplib.c

@@ -720,21 +720,12 @@ static int side_set(lua_State *L)
 		side->rowoffset = luaL_checkfixed(L, 3);
 		break;
 	case side_toptexture:
-		if (lua_isstring(L, 3))
-			side->toptexture = R_TextureNumForName(lua_tostring(L, 3));
-		else
 		side->toptexture = luaL_checkinteger(L, 3);
 		break;
 	case side_bottomtexture:
-		if (lua_isstring(L, 3))
-			side->bottomtexture = R_TextureNumForName(lua_tostring(L, 3));
-		else
 		side->bottomtexture = luaL_checkinteger(L, 3);
 		break;
 	case side_midtexture:
-		if (lua_isstring(L, 3))
-			side->midtexture = R_TextureNumForName(lua_tostring(L, 3));
-		else
 		side->midtexture = luaL_checkinteger(L, 3);
 		break;
 	case side_repeatcnt: