Add compilation instructions for MacOS

Fix for AMD GPU detection on MacOS X

update windows compile guide  

add missing nvidia help to usage.md

add NVIDIA cli options to the help message

Update gpu.hpp

Fix indent on hash rate report.

Fix for AMD GPU detection on MacOS X
On MacOS X the platform is reported as Apple, and the vendor is reported as AMD.

Fix crash on FreeBSD (#177)

Fixing the compile error on MacOS X

Fix uninitialized memory accces

fix appvoyer

Uninitialized memory access is UB in C/C++, fix it.

This change fix #177 and compiler warning too.

add explicit note that VSC v141 must be used for AMD and CPU compile.

Remove the execution of the binary at the end of the CI test. This is only currently a temporary solution.

Add cheksums

Add cheksums

Add windows exit

Add windows exit

update windoes compile guide

Point to new xmr-stak-dep precompiled binaries if CUDA9 is used.

fix windows compile documentation

fix broken windows compile with v140

- add copy of openssl libs to appvoyer CI tests
- update windows compile documentation

add microhttpd libs explicit to `xmr-stak-c`

Update docs

fix max work size shown to user

rename to make it clearer that this is a linux binary

handle OpenCL errors

fix OpenCL compatibility

The max work size shown to the user was the hardware maximum but not take in account thet some kernel spwning 8 times more threads per work group than configured by the user.

- handle opencl errors to avoid unexpected behaviors
- remove code duplicatio nwithin the some method

- enforce that only host side OpenCl 1.2 functions are used if the miner is compiled with `XMR-STAK_COMPILE=generic`
- update documentation
- add CMake option `XMR-STAK_COMPILE` to windows

Fix GPU result crash

Fix gpu result crash

fix wrong cuda binary arch detection