Add new plugin for voting system.

Allows voting session in group conversations.

plugins/vote.lua

@@ -0,0 +1,85 @@
+local _file_votes = './data/votes.lua'
+
+function read_file_votes ()
+	local f = io.open(_file_votes, "r+")
+	if f == nil then
+		print ('Created voting file '.._file_votes)
+		serialize_to_file({}, _file_votes)
+	else
+		print ('Values loaded: '.._file_votes)
+		f:close()
+	end
+	return loadfile (_file_votes)()
+end
+
+function clear_votes (chat)
+	local _votes = read_file_votes ()
+	_votes [chat] = {}
+	serialize_to_file(_votes, _file_votes)
+end
+
+function votes_result (chat)
+	local _votes = read_file_votes ()
+	local results = {}
+	local result_string = ""
+	if _votes [chat] == nil then
+		_votes[chat] = {}
+	end
+	for user,vote in pairs (_votes[chat]) do
+		if (results [vote] == nil) then
+			results [vote] = user
+		else
+			results [vote] = results [vote] .. ", " .. user
+		end
+	end
+	for vote,users in pairs (results) do
+		result_string = result_string .. vote .. " : " .. users .. "\n"
+	end
+	return result_string
+end
+
+
+function save_vote(chat, user, vote)
+	local _votes = read_file_votes ()
+	if _votes[chat] == nil then
+		_votes[chat] = {}
+	end
+	_votes[chat][user] = vote
+
+	serialize_to_file(_votes, _file_votes)
+	
+end
+
+function run(msg, matches)
+	if (matches[1] == "ing") then
+		if (matches [2] == "reset") then
+			clear_votes (tostring(msg.to.id))
+			return "Voting statistics reset.."
+		elseif (matches [2] == "stats") then
+			local votes_result = votes_result (tostring(msg.to.id))
+			if (votes_result == "") then
+				votes_result = "[No votes registered]\n"
+			end
+			return "Voting statistics :\n" .. votes_result
+		end
+	else
+		save_vote(tostring(msg.to.id), msg.from.print_name, tostring(tonumber(matches[2])))
+		return "Vote registered : " .. msg.from.print_name .. " " .. tostring(tonumber(matches [2]))
+	end
+end
+
+return {
+    description = "Plugin for voting in groups.", 
+    usage = {
+	    "!voting reset: Reset all the votes.",
+	    "!vote [number]: Cast the vote.",
+	    "!voting stats: Shows the statistics of voting."
+    },
+    patterns = {
+	    "^!vot(ing) (reset)",
+	    "^!vot(ing) (stats)",
+	    "^!vot(e) ([0-9]+)$"
+    }, 
+    run = run 
+}
+