Added modified_parameters property to Specifications
Added modified_parameters property to Specifications

Working by testing parameter values for equality with the default
values. Includes the first dictionary comprehension committed in
Topographica (Python 2.7+).

ioam/topographica,ioam/topographica,mjabri/topographica,mjabri/topographica,mjabri/topographica,mjabri/topographica,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,ioam/topographica,ioam/topographica,ioam/topographica,mjabri/topographica