Allow importing old databases.

Currently:
- Minetest (`ipban.txt')
- xban v1 (`players.iplist')

importers/minetest.lua

@@ -0,0 +1,29 @@
+
+function xban.importers.minetest()
+	local f, e = io.open(minetest.get_worldpath().."/ipban.txt")
+	if not f then
+		return false, "Unable to open `ipban.txt': "..e
+	end
+	for line in f:lines() do
+		local ip, name = line:match("([^|]+)%|(.+)")
+		if ip and name then
+			local entry
+			entry = xban.find_entry(ip, true)
+			entry.banned = true
+			entry.reason = "Banned in `ipban.txt'"
+			entry.names[name] = true
+			entry.names[ip] = true
+			entry.time = os.time()
+			entry.expires = nil
+			entry.source = "xban:importer_minetest"
+			table.insert(entry.record, {
+				source = entry.source,
+				reason = entry.reason,
+				time = entry.time,
+				expires = nil,
+			})
+		end
+	end
+	f:close()
+	return true
+end