- Update open_table for mapistore backend folder prototype to take
  TALLOC_CTX memory context as first parameter

- Add open_table implementation in mapistore_python backend
Add mapistore python implementation for folder.get_child_count
Add mapistore python implementation for table.set_columns
Use hexadecimal version prefixed with 0x rather than decimal value
for unmapped properties.
mapistore_test: Missing brake in a switch
mapistore_test: Load loadparm defaults after setting the debug level

Otherwise it is awasy very chatty during initialization, no matter
what the -d option is
- Update get_row for mapistore backend folder prototype to take
TALLOC_CTX memory context as first parameter

- Add get_row mapistore python implementation
- Add PyObject to C type conversion function for properties data
- Update makepropslist with a reverse property name -> value mapping
- Update open_message for mapistore backend folder prototype to take
TALLOC_CTX memory context as first parameter

- Add open_message mapistore python implementation
Fix incorrect check after talloc_strdup call for folder object
mapistore/py: Initial implementation for OXIO adapter backend
mapistore_test: Add call to list_context - currently it is a non-failure
mapistore_test: Add context with our test ID, so we could search for it later

With this backend now correctly resolves 0xdeadbeef to opt_uri
in Context.get_path(fmid)
mapistore/py: Print folder ids as HEX when logging
mapistore/py: Don't print error when we don't have a path for given FMID

It is just backend don't know about this FMID, and it is responsibility
for the caller to decide what to do - is it critical or not
mapistore_test: Helper to find any child FMID for a folder

It is to be used for testing later
mapistore/oxio: Fix exception in Folder.create_folder()
- Update get_message_data for mapistore backend message prototype to take
TALLOC_CTX memory context as first parameter

- Add get_message_data mapistore python implementation
Remove commented code
Update mapistore_python_object_type enumeration and remove deprecated
entries
Call Py_DECREF on proplist in set_columns (new reference)