remove useless module dependences
use format but not ++++
add Function And Fn
rebuild fetchall fetchone
fetchone return None if data is None
add shortcut for models
add function avg
no func shortcuts for Models
setattr functions when make instances
typofixed in comment
add lcase
add tests for functions
v0.3.1 changes
v0.3.1 ready
functions docs added
Merge branch 'dev'

* dev:
  functions docs added
  v0.3.1 ready
  v0.3.1 changes
  add tests for functions
  add lcase
  typofixed in comment
  setattr functions when make instances
  no func shortcuts for Models
  add function avg
  add shortcut for models
  fetchone return None if data is None
  rebuild fetchall fetchone
  add Function And Fn
  use format but not ++++
  remove useless module dependences