Fixes #945 - monkeys can't ventcrawl

Ventcrawl will now tell you which items prevent you from crawling if it
fails due to that

code/modules/mob/living/living.dm

@@ -648,7 +648,7 @@ default behaviour is:
 	src << "<span class='notice'>You are now [resting ? "resting" : "getting up"]</span>"
 
 /mob/living/proc/is_allowed_vent_crawl_item(var/obj/item/carried_item)
-	return isnull(get_inventory_slot(carried_item))
+	return (get_inventory_slot(carried_item) == 0)
 
 /mob/living/simple_animal/spiderbot/is_allowed_vent_crawl_item(var/obj/item/carried_item)
 	if(carried_item == held_item)
@@ -716,10 +716,12 @@ default behaviour is:
 		return
 
 	if(!ignore_items)
+		var/list/badItems = list()
 		for(var/obj/item/carried_item in contents)//If the monkey got on objects.
-			if(is_allowed_vent_crawl_item(carried_item))
-				continue
-			src << "<span class='warning'>You can't be carrying items or have items equipped when vent crawling!</span>"
+			if(!is_allowed_vent_crawl_item(carried_item))
+				badItems += carried_item.name
+		if(badItems.len)
+			src << "<span class='warning'>Your [english_list(badItems)] prevent[badItems.len == 1 ? "s" : ""] you from ventcrawling.</span>"
 			return
 
 	if(isslime(src))

html/changelogs/Kelenius-crawlFix.yml

@@ -0,0 +1,36 @@
+################################
+# Example Changelog File
+#
+# Note: This file, and files beginning with ".", and files that don't end in ".yml" will not be read. If you change this file, you will look really dumb.
+#
+# Your changelog will be merged with a master changelog. (New stuff added only, and only on the date entry for the day it was merged.)
+# When it is, any changes listed below will disappear.
+#
+# Valid Prefixes: 
+#   bugfix
+#   wip (For works in progress)
+#   tweak
+#   soundadd
+#   sounddel
+#   rscadd (general adding of nice things)
+#   rscdel (general deleting of nice things)
+#   imageadd
+#   imagedel
+#   maptweak
+#   spellcheck (typo fixes)
+#   experiment
+#################################
+
+# Your name.  
+author: Kelenius
+
+# Optional: Remove this file after generating master changelog.  Useful for PR changelogs that won't get used again.
+delete-after: True
+
+# Any changes you've made.  See valid prefix list above.
+# INDENT WITH TWO SPACES.  NOT TABS.  SPACES.
+# SCREW THIS UP AND IT WON'T WORK.
+# Also, all entries are changed into a single [] after a master changelog generation. Just remove the brackets when you add new entries.
+# Please surround your changes in  double quotes ("), as certain characters otherwise screws up compiling. The quotes will not show up in the changelog.
+changes: 
+  - bugfix: "Monkeys can ventcrawl once again."