Before this change, expression_instance would not be set when expression is
modified, leading to either non-applied filter expression (when no
expression_instance existed) or use of an outdated expression.
Use a volatile attribute to store the expression: it does not change the
amount of work needed to load the Expression instance (pickle is the raw
python expression as text) and it remove data duplication in exported
documents.

Move from SQLCatalog to ERP5Catalog as the default Catalog inside ERP5.
The major difference is use of Products.ERP5Type.Core.Folder as Catalog
base class.

Significant addition/changes in
-------------------------------

  ERP5Catalog class:
    Inherit from Catalog class from Products.ZSQLCatalog.SQLCatalog instead of copy-pasting the whole code again.
    Monkey patch some property setters and getters to maintain consistency
    Override getCatalogMethodIds cause it uses global variable in SQLCatalog.Catalog
    Add FilterDict and Filter class to have consistency with `filter_dict` attribute of SQLCatalog

  BusinessTemplate:
    Update BusinessTemplate installation with updated filter_dict
    Also, use dynamic migration while installing the catalog method objects for
    bt5. This way we have SQL Methods migrated just after installation.

  Tests:
    Update tests according to changes in portal_catalog

  SQLCatalog, testZSQLCatalog:
    Cleanup for unusable functions