Require the memory implementations to implement a share operation. This allows
us to remove the fallback share implementation which uses a different allocator
implementation and complicates things too much.
Update design doc a bit.
Make the fallback copy use the same memory allocator as the original object.
Improve some docs.
Require an alloc function when registering an allocator.
Remove gst_memory_allocator_get_default() and merge the feature in
gst_memory_allocator_find()
Fix locks on the hashtable.
Remove defined but not-implemented gst_memory_span() method.
Rename the GstMemoryImpl to GstMemoryAllocator because that's really what it is.
Add an alloc vmethod to the allocator members.
Improve registration of allocators.
Add methods to get and set the default allocator
Always use an allocator to allocate memory, use the default allocator when NULL
is passed.
Add user_data to the allocator Info so that we can pass extra info to the
allocator new method.
Allow for automatic merging of memory block in the _map function and automatic
freeing of the temporary memory.
Remove some unneeded functions.
Add possibility to force writable spanned memory.
