First minor version increment. Add new ds_darray object, a dynamic ar…

…ray.

ds_darray is the first data structure in the library, but currently has a fairly simple API.
A constructor and destructor are provided which use ds_alloc, and a push and resize function to provide the usual dynamic array interface.
An at function which does bounds checking is also provided.
Finally, a macro DS_DARRAY_AS is provided which expands to the data member of the ds_darray cast to a T* for some type T.

Support for custom allocators and a default allocator using malloc/re…

…alloc/free.

Just a README and a header with version macros.