dbff: Read and write flat file databases in CSV format

This class can be used to read and write flat file databases in a tagged CSV format. It can serve as a standalone PHP database replacement for simple and small applications or dynamic web pages.
It can create and maintain files with a given data definition for column names and types.
The class can perform queries to search CSV file records with fields that match a given condition. The search condition can use several kinds of comparison operands similar to SQL and with functions like Select (with and/or/sort), insert, update, delete, commit and rollback.
Supported datatypes are String, Integer, Number and Date formats.
Data validation are performed on insert/update and additional checks like Not Null, min, max, list and PK/UK keys can be defined. It is also possible to define an autoincremental key and record encryption.