Add initial code for base_quest, quest, side_quest.

Also, fix typo.

bot.py

@@ -23,7 +23,7 @@ def start(bot, update):
     text = f"Hello {name}!\n" + \
         "Welcome to Questable. To get started, check /help."
     custom_keyboard = [
-            ['Add Quest', 'Add Side-quests'],
+            ['Add Quest', 'Add Side-quest'],
             ['List Quests', 'List Side-quests']
             ]
     reply_markup = telegram.ReplyKeyboardMarkup(custom_keyboard)

questable.py

@@ -0,0 +1,30 @@
+from datetime import datetime
+
+
+class base_quest():
+    TABLE = None
+
+    def __init__(self, db, chat_id, qid, name=None, imp=None, diff=None,
+                 state=None, date=None):
+        self.DB = db
+        self.CHAT_ID = chat_id
+        self.name = name
+        self.QID = qid
+        self.imp = imp
+        self.diff = diff
+        self.state = state
+        if date:
+            if isinstance(date, datetime):
+                self.date = date
+            else:
+                self.date = datetime.fromtimestamp(date)
+        else:
+            date = None
+
+
+class quest(base_quest):
+    TABLE = "quests"
+
+
+class side_quest(base_quest):
+    TABLE = "side_quests"