Calling dir() on a Structure includes Fields

[rtzoeller]

Based on this blogpost, it may be desirable to have Structure implement __dir__, and add the dynamic fields to the returned list. This promotes field discovery when not looking at the structure implementation, and may help improve autocomplete in some cases.

[coveralls]

Coverage decreased (-0.05%) to 98.529% when pulling 12202ba on rtzoeller:dir_support into 1912bca on digidotcom:master.

[posborne]

Can you add a simple test to ensure that this functionality does not regress in the future?

[rtzoeller]

Realized this implementation is broken on Python2, as object does not provide a __dir__ method. Looking at alternative solutions.

[coveralls]

Coverage increased (+0.006%) to 98.586% when pulling 7c915fb on rtzoeller:dir_support into 1912bca on digidotcom:master.