Added PHP8 and MySQL support

• added php8 support
• added MySQL support
• added TreeStore support (json string)
• fixed some bugs in the query parser
• changed the query syntax slightly

Fixes query parser

There were still some bugs in the query parser, fixed those and added more tests. This release changes the query syntax slightly: like and 'not like' are now replaced by '=' and '!'.

Hierarchical structured object store.

Although this is a first release I tagged it at 3.0, to be in sync with the rest of the ARC components.