Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().
Remove those uses, as they are no longer required.
https://bugzilla.gnome.org/show_bug.cgi?id=686161
And remove the 'joinable' argument from g_thread_new() and
g_thread_new_full().
Change the wording in the docs. Clarify expectations for
(deprecated) g_thread_create().
These were the last users of the dynamic allocation API.
Keep the uses in glib/tests/mutex.c since this is actually meant to test
the API (which has to continue working, even if it is deprecated).
https://bugzilla.gnome.org/show_bug.cgi?id=660739