MySQL query, paging and caching helper

This class can query and cache MySQL results to be paginated.

It can execute arbitrary SQL queries or assemble SELECT, INSERT, UPDATE and DELETE queries from lists of parameters that define tables, fields, field values and condition clauses.

The SELECT query results may be cached in files with the stored values encoded in JSON format.

The class can also generate links to browse pages of query result listings split over multiple pages of a limited number of results per page.