New doc section: codesnippets / Advanced Examples

Presents code examples that use the instaloader module for more advanced tasks
than what is possible with the Instaloader command line interface.

Presents #46, #56, #110, #113, #120, #121.

docs/codesnippets/121_since_until.py

@@ -0,0 +1,17 @@
+from datetime import datetime
+from itertools import dropwhile, takewhile
+
+import instaloader
+
+L = instaloader.Instaloader()
+
+posts = L.get_hashtag_posts('milfgarden')
+# or
+# posts = instaloader.Profile.from_username(L.context, PROFILE).get_posts()
+
+SINCE = datetime(2015, 5, 1)
+UNTIL = datetime(2015, 3, 1)
+
+for post in takewhile(lambda p: p.date > UNTIL, dropwhile(lambda p: p.date > SINCE, posts)):
+    print(post.date)
+    L.download_post(post, '#milfgarden')