parsing over enum field option types

master branch 'appnexus/pyrobuf' merge with the following refinements:

Add module_name option (for static type checking) appnexus#140
IntEnum class appnexus#102
HexValue parsing appnexus#144
Parsing over atmoic field option types appnexus#154
Fix parsing custom field options
Fix using more than 64 fields with unused index appnexus#135
Skip building for include files