Add pydblite dialect

[Z M]

I don't know how people will feel about this idea. But, I think SqlAlchemy should support a pure python database. There are certain python environments that wont support sqlite and it can be very costly to deploy another database in.

Having a consistent API (SqlAlchemy), would allow a projected deployed in such a restricted environment to take advantage of the great features of SqlAlachemy and allow simple porting to another environment (with a better database back-end) if/when the project outgrows it.

[Mike Bayer]

not a problem at all. Use the guidelines at https://bitbucket.org/zzzeek/sqlalchemy/src/7189d0bc82598c2d6dcbb55b054837416db2ee7d/README.dialects.rst?fileviewer=file-view-default and dialects are added liberally to the lists at http://docs.sqlalchemy.org/en/latest/dialects/index.html#external-dialects .