Remove .md and image files and move python files into main chapter folders

thinkcspy/Chapter-9-Exercises/Python-files/Problem18.py

@@ -1,24 +0,0 @@
-# Runestone.Academy thinkcspy course
-# Chapter 9
-# Problem 18
-
-import string
-
-def encrypt(msg, code):
-    alpha = string.ascii_lowercase
-    newStr = ""
-    pos = 0
-    msg = msg.lower()
-    
-    for char in msg:
-        if char in alpha:
-            pos = alpha.index(char)
-            newStr += newAlpha[pos]
-        else:
-            newStr += char    # no rules apply so keep the character
-
-    return newStr
-
-newAlpha = "qwertyuiopasdfghjklzxcvbnm"
-
-print(encrypt("Hello World!", newAlpha))