removed fragment_dma_link_chain, and started first steps linking DMAFragements in dam_fragment_list, also removed some invalid return codes
restructuring of strides to u32 (which a helper structure)
and move of some defines to inline functions (type checking)
moved things arround
added some exports
made a separate dma_fragment module
added implementations for: dma_fragment_cache_fetch and dma_fragment_cache_return
restructured layout of source, so that allocation and filling in data
are closer together...