Missing methods for returning excess in Alloc

[TimDiekmann]

Returning Excess when allocating is useful for collections like (Raw)Vec. Currently, only these methods are provided:

• alloc_excess
• realloc_excess

In order to make those collection work with the excess api, these methods have to be added:

• alloc_zeroed_excess
• grow_in_place_excess
• shrink_in_place_excess

[adlerd]

Is there a discussion somewhere about why X_excess isn't just called X; i.e., all of the "default" functions return the actual allocation size which can be used or ignored? Are there allocators which have different behavior when _excess is called (and should that behavior be supported)?

[TimDiekmann]

@adlerd Sorry, somehow I haven't noticed your question. Yes, #17 proposes to remove the usable_size API and rename the x_excess to x.