New module for SQLite import & export

This module will export (and, ahem, import) files of data and results
from and SQLite database. The eventual aim is to make Salstat’s data
persistent, i.e., save becomes irrelevant.
Inits now available in gridbase

The gridbase module didn’t access the inits properly so couldn’t save
or load data. It now has access but testing would be useful.
Salstat roadmap

This is the roadmap for Salstat. Feature requests are welcomed to
alan@salstat.com.
Changes to support other changes in salstat.py

Changes here included adding a toolbar picture to run an arbitrary test
(in this case, save the metadata in SQLite format); and also allow the
gridbase module to access inits.