release 2.8.2

increase version to 2.8.2

OpenCL: fix the fix for the blockchain driver

 #2229 was not solving the issues

- revert #2229
- introduce the working fix

OpenCl: fix blockchain driver support

The OpenCl version of the blockchain driver is not understanding if
apointer to a pointer points into shared memory and throw an error
during the compilation.

- revert the usage of the struct to group all shared memory arrays

release 2.8.1

update algorithm documentation

- add more information if a algorithm derives from an other
- update `pools.tpl`

update version to 2.8.1

OpenCl: optimize cn_gpu

Add seperate kernel to prepare the scratchpad memory.

CUDA: update cn_gpu auto adjust values

CUDA/OpenCL: use shared mem object

better variable nameining

Optimize the auto adjustment for cn_gpu based on precomputed occupancy
values from CUDA10.

Combine the shared memory for a hash within one struct.
Reduce the shared memory footprint per hash by 64 byte.

- rename variable names like `b` and `bb` to something with a little bit
of meaning.

 add Zelerius coin

add cryptonight_v8_half

OpenCL: optimize cn_gpu

fix groestl, skein and blake

Optimize cn_gpu

based on the suggestion from @xmrig https://github.com/xmrig/xmrig-amd/commit/db4e169f3a78f273abf89ea8cf5bba7eccf1490b

This PR replaces #2196 and add support for zelerius.

- add cryptonight_v8_half
- re-add stellite and masari to the supported coins

remove cn_turtle as native POW 

refactor POW definition

cn_gpu: disable auto suggestion for CPU

cryptonight_turtle is only cryptonight_v8 with a different scratchpad,
iteration and mask value.
We are using now the new machanism to describe such derived POWs.

A POW is now defined by a function `f` and three degrees of freedom `f(iteration, scratchpad, mask)`.
`f` is the base algorithm like `cryptonight, cryptonight_gpu`
An easy to pars snytax to write the full POW definition down is: `cryptonight_gpu:0x0000c000:0x00200000:0x001fffc0`

This change make it very easy to integrate the new trend of variate the
number of iteations or the scratchpad size without modifying the full
code.

To avoid that a miner is waisting power with there CPU to mine cn_gpu the
auto suggestion will comment out the config.

OpenCl: use user defined unroll in cn_gpu

OpenCL: fix invalid work group size

OpenCL: fix groestl

@xmrig provided the information that the driver 19.2.1 for vega also
create invalid results if pragma unroll is used for the groestl algo.

- use the user defined unroll
- auto suggestion:
  - only tune for cn_gpu if this is the main user
currency (after a fork)
  - set unroll to 1 for cn_gpu