XMR-Stak 2.3.0 RC

Co-authored-by: psychocrypt <psychocryptHPC@gmail.com>
Co-authored-by: fireice-uk <fireice-uk@users.noreply.github.com>
Co-authored-by: Lee Clagett <code@leeclagett.com>
Co-authored-by: curie-kief <curie-kief@users.noreply.github.com>

fix shadowed variable

A redefinition of a variable in a local scope avoid that the intensity is rounded to a multiple of the work size.

Fix #1122 - HTML report violates XML rules

CUDA: reduce startup time

OpenCL compile cache

Comment cleanup

Reduce OpenCL start time by using a self made compiler cache.

- store compiled OpenCL binary
- load OpenCl binary if available

- add project picosha2
- add license notes for picosha2

- reduce startup time for multi gpu systems
- initialize the GPU memory non concurrent

fix broken memchunk feature

fix double definition of define `MEM_CHUNK`

fix compile with OpenCL 1.1

add Mesa OpenCL support

add OpenCL compatibility mode

guard error types those are only defined in OpenCL >1.1

- add new option `comp_mode` to the amd config
- disable `if guards` within opencl kernel if `comp_mode : false`

allow usage of Mesa OpenCl

AMD: option `mem_chunk`and new `strided_index`

AMD: reduce register usage

fix missing message in log file

- add new option for `strided_index`
- add additional option if `strided_index == 2` to controll the memory chunk with

initialize the log file as fast as possible after the start of the miner

reduce usage of registers: based on the suggestion of @enerc77

Add rig identifier

Add video guide

disable OSX CI tests

Currently the CI fails due to the issue
```
Error: homebrew/science was deprecated. This tap is now empty as all its formulae were migrated.
The command "if [ $TRAVIS_OS_NAME = osx ]; then brew update; brew tap homebrew/science; fi" failed and exited with 1 during .
```

Until the fix is implemented the OSX tests will be disabled.

Update compile process (Windows)

Update compile_Linux.md

improve AMD auto suggestion for AEON

speedup Volta