Detrusty

- Add more functions to the Config class in order to avoid direct access of its attributes
- Move version information inside the package
- Add favicon to pages served when running DeTrusty as a service

- Complete the string representation of a query to also include GROUP BY, HAVING, ORDER BY, LIMIT, and OFFSET
- Fix variable check for GROUP BY and ORDER BY

- Use StreamHandler for loggers if FileHandler cannot be established

- Fix query result format issue while creating the source descriptions

- Merge parsers
- DeTrusty uses only one parser now, hence,
- Deprecate sparql_one_dot_one parameter of run_query()
- Add support for parsing SPARQL queries with comments
- Fix issue with COUNT(*)

- Add complex expressions
- Update return format to match with the SPARQL specification, i.e., include type and datatype, not just the value
- Fix minor issues in aggregate functions
- Fix implicit grouping
- Fix error of executing a query with no matched source if only rdf:type statement in query
- Fix issue with non-grouped optional variables
- Fix filters
- ... for URIs
- ... over optional variables
- Fix wrong splitting of VALUES clause when using multiple variables
- Throw error if
- projected variables are not grouped or aggregates
- projected variables are not defined in the body
- variables in ORDER BY are not projected
- variables in GROUP BY are not defined in the body
- Add functionality for ordering by multiple variables
- Adjust Xorderby to use datatypes