Merge pull request #1 from antolikjan/master

Added parameter replacement and references. (Need to remove print statement, which is not Python 3 compatible.)
removed print statement
Added a unit test for the use of `ParameterReference`
Documentation tweaks
Updated version number to 0.2.0
Missed a version number in docs
Merge branch 'master' of https://github.com/antolikjan/parameters into lazyref

Conflicts in parameters/__init__.py resolved by hand.
Corrected bug with complex nested references