Removed update/insert/delete

I don't use them and AFAIK this module has no other users

tests_dir/rename_insert1.py

@@ -1,4 +0,0 @@
-p1=people.rename({"id":"ido"})
-people.insert((123,"lala",0,31))
-assert people!=p1
-people.delete("id==123")

tests_dir/rename_insert2.py

@@ -1,4 +0,0 @@
-p1=people.rename({"id":"ido"})
-p1.insert((123,"lala",0,31))
-assert people!=p1
-people.delete("id==123")

tests_dir/update.py

@@ -1,16 +0,0 @@
-p1=people
-p2=p1.rename({'id':'i'})
-p2=p2.rename({'i':'id'})
-assert p1==p2
-assert p1._readonly
-assert p2._readonly
-# It is VERY important to not change the original relations
-# or other tests might fail randomly, since the relations are
-# only loaded once
-
-p2.update('age==20', {'age':50})
-assert p2._readonly == False
-assert p1!=p2
-p3 = p2.selection('age!=50')
-p4 = p1.selection('age!=20')
-assert p3==p4