ActionMap: lookup_action(): Fix the reference counting.

* gio/src/actionmap.hg: Use refreturn.
giomm: Add VariantParseError.
Remove obsolete comment.
Fix the build after previous commit
Regenerated enums .defs files
Regenerated methods .defs files
Regenerated extra .defs files
Regenerated docs .xml files
Gio::Settings: Add get/set_uint().
Gio::File: Add measure_disk_usage() and measure_disk_usage_async().

* gio/src/file.[hg|ccg]: Wrap g_file_measure_disk_usage(),
  g_file_measure_disk_usage_async() and
  g_file_measure_disk_usage_finish(), based on the copy() and
  copy_async() methods, which also have 2 slots.
* tools/m4/convert_glib.m4: Add a conversion for guint64&.
Spawn: Use the new SPAWN_DEFAULT instead of 0.

* glib/src/spawn.hg: The value is the same, however.
tools: h2def.py: Handle *_DEPRECATED_IN_*_FOR (*)
Regenerated methods .defs files
2.37.93
ByteArray: Add some tests for methods returning self.

* tests/Makefile.am:
* tests/glibmm_bytearray/main.cc: New file with tests. These are
failing now.
ByteArray: Fix refcount problems.

* glib/src/bytearray.hg: Add refreturn to methods returning self.
.gitignore: Update.

* .gitignore: Ignore the files generated by Automake testing
infrastructure.
Gio::ActionMap: Fix a reference-counting problem.

* gio/src/actionmap.hg: add_action_vfunc(): Add a custom _CONVERSION()
  that takes a reference, just for this vfunc. We would have
  seen the need for this before if it had used a const & instead
  of passing the RefPtr by value, which we probaby cannot change
  now without breaking ABI.
Add a comment
Gio::MenuItem: get/set_attribute(): Deprecated for *_value() methods.

* gio/src/menuitem.hg: set_attribute(): Deprecate this in favour of
  set_attribute_value() though it was previously the other way around.
  Add get_attribute_value() and deprecate get_attribute() in favour
  of it.
  This lets us, one day, remove those set_attribute() and
  get_attribute() methods and replace them with more pleaseant
  templated set/get_attribute() methods that just call the
  *_value() methods, as in Gio::Action.