Global code ovehaul - remove CAS and other, add 15 minute greet check

- Remove CAS, as it no longer works for us
- Remove other checks
- Implement 15 minute greet timeout check
- Fix chat logos
- Ditch thirdparty logger, use stdlib log facility wrapper for logging

vendor/github.com/NicoNex/echotron/v3/dispatcher.go

@@ -26,29 +26,8 @@ import (
 	"log"
 	"net/http"
 	"net/url"
-	"sync"
 )
 
-type smap struct {
-	m sync.Map
-}
-
-func (s *smap) load(id int64) (Bot, bool) {
-	bot, ok := s.m.Load(id)
-	if ok {
-		return bot.(Bot), ok
-	}
-	return nil, ok
-}
-
-func (s *smap) store(id int64, bot Bot) {
-	s.m.Store(id, bot)
-}
-
-func (s *smap) delete(id int64) {
-	s.m.Delete(id)
-}
-
 // Bot is the interface that must be implemented by your definition of
 // the struct thus it represent each open session with a user on Telegram.
 type Bot interface {
@@ -64,12 +43,11 @@ type NewBotFn func(chatId int64) Bot
 // associated with each chatID. When a new chat ID is found, the provided function
 // of type NewBotFn will be called.
 type Dispatcher struct {
-	// sessions   map[int64]Bot
-	sessions   smap
+	api        API
 	newBot     NewBotFn
 	updates    chan *Update
 	httpServer *http.Server
-	api        API
+	sessions   smap[int64, Bot]
 }
 
 // NewDispatcher returns a new instance of the Dispatcher object.