Issue new release of QuantEcon.py

[mmcky]

I am about to issue a new release of QuantEcon.py and I am thinking of incrementing our major version number to 0.4.0 due to the addition of a new subpackage (optimize). This got me thinking that the way we use version numbers in my head is:

1. major version = currently 0 to indicate library is in active development
2. minor version = new subpackage or backward incompatible change (currently 3)
3. minor-minor version = new features and bug fixes (currently 9)

Does everyone agree with this logic? @jstac @oyamad

[jstac]

Sounds good to me @mmcky

[davidrpugh]

@mmcky your logic seems very similar to the ideas in semantic versioning.

[mmcky]

thanks for the link @davidrpugh. Great.