Merge pull request #39 from chakrit/master

Adds support for the NOT IN operator.
Fix broken internal link in docs ref #38
Allow arbitrary nodes in orderby. Ref. #37
v0.8.2

Fix #38 - Nodes module link broken in doc.
Fix #37 - order by text node
Fix #36 - .copy() fails on text() fields
Fix #35 - order by function result
Fix #31 - regression on named parameters in db.text() sql strings
remove debugger statement
fix package version in Makefile
v0.8.3 - closes #40