Presenting a revised data stores and oh my, a generic speech recognition API! I wonder what we can do with this now...

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@18979 65c4cc65-6c06-0410-ace0-fbb531ad65f3

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+Asterisk Channel Data Stores
+============================
+
+* What is a data store?
+
+A data store is a way of storing complex data (such as a structure) on a channel
+so it can be retrieved at a later time by another application, or the same application.
+
+If the data store is not freed by said application though, a callback to a destroy function
+occurs which frees the memory used by the data in the data store so no memory loss occurs.
+
+* A datastore info structure
+static const struct example_datastore {
+       .type = "example",
+       .destroy = callback_destroy
+};
+
+This is a needed structure that contains information about a datastore, it's used by many API calls.
+
+* How do you create a data store?
+
+1. Use ast_channel_datastore_alloc function to return a pre-allocated structure
+   Ex: datastore = ast_channel_datastore_alloc(&example_datastore, "uid");
+   This function takes two arguments: (datastore info structure, uid)
+2. Attach data and destroy callback to pre-allocated structure.
+   Ex: datastore->data = mysillydata;
+       datastore->destroy = callback_destroy;
+3. Add datastore to the channel
+   Ex: ast_channel_datastore_add(chan, datastore);
+   This function takes two arguments: (pointer to channel, pointer to data store)
+
+Full Example:
+
+void callback_destroy(void *data)
+{
+	free(data);
+}
+
+struct ast_datastore *datastore = NULL;
+datastore = ast_channel_datastore_alloc(&example_datastore, NULL);
+datastore->data = mysillydata;
+datastore->destroy = callback_destroy;
+ast_channel_datastore_add(chan, datastore);
+
+NOTE: Because you're passing a pointer to a function in your module, you'll want to include
+this in your use count. When allocated increment, when destroyed decrement.
+
+* How do you remove a data store?
+
+1. Find the data store
+   Ex: datastore = ast_channel_datastore_find(chan, &example_datastore, NULL);
+   This function takes three arguments: (pointer to channel, datastore info structure, uid)
+2. Remove the data store from the channel
+   Ex: ast_channel_datastore_remove(chan, datastore);
+   This function takes two arguments: (pointer to channel, pointer to data store)
+3. If we want to now, free the memory or do stuff to the data on the data store
+   If we do then we will want to unset the data and callback
+   Ex: datastore->data = NULL;
+       datastore->destroy = NULL;
+4. Free the data store
+   Ex: ast_channel_datastore_free(datastore);
+   This function takes one argument: (pointer to data store)
+
+* How do you find a data store?
+
+1. Find the data store
+   Ex: datastore = ast_channel_datastore_find(chan, &example_datastore, NULL);
+   This function takes three arguments: (pointer to channel, datastore info structure, uid)