* avoid using with a lot of data as it's really slow, prefer
* block_ChainLastAppend
* - block_ChainLastAppend : use a pointer over a pointer to the next blocks,
* and update it.
* - block_ChainRelease : release a chain of block
* - block_ChainExtract : extract data from a chain, return real bytes counts
* avoid using with a lot of data as it's really slow, prefer
* block_ChainLastAppend
* - block_ChainLastAppend : use a pointer over a pointer to the next blocks,
* and update it.
* - block_ChainRelease : release a chain of block
* - block_ChainExtract : extract data from a chain, return real bytes counts