#105 Ensure database is changed at each install

[Nicolas Hainaux]

So far, mathmaker creates a copy of mathmaker.db-dist (as mathmaker.db) if mathmaker.db-dist is newer than mathmaker.db. This is not enough, in some cases it does not ensure the replacement of the old version by the newer one.
Possible solutions:

1°) Include the version number in a dedicated field in the database

• replace the time condition to trigger the copy by a check of this version number
• the script toolbox/build_db.py create the copy at the end of its process
• inclusion of the version number in the database should be made by setup.py

2°) Looks better: include the version number in the name of the database, like mathmaker-0.7.2dev1.db

• the script toolbox/build_db.py create the copy including version number in the name, at the end of its process
• mathmaker will only check if there's a file with the matching version in the name (no time condition), if not it will create the copy (and delete older versions).

3°) Even better: use a post-install script to create the copy right after install. Check it works also for upgrades.