add Mesa OpenCL support

add OpenCL compatibility mode

- 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

fix output of gpu name

Update FAQ.md

Fix Disabling AMD GPUs

The AMD jconf.cpp would only accept an array. The config sample, and the nvidia and cpu config work with the value 'null', as they accept a 'kNullType'. This means at current, AMD GPUs could not be turned off, the config file wouldn't parse on load.

This change makes AMD consistent with the others, and can now be disabled.

Add info about sysctl.conf so that the settings are preserved.

Moved section about Windows changing the working directory higher.

fix that the GPU name is printed before the name is querried from OpenCL

- enable L1 cache for Nvidia Volta GPUs and newer
- remove explicit cache controll for Volta GPU and newer

This pull request increases the hash rate for Volta GPUs by ~5%

increase the intensity limit for AEON

avoid nonce overlapping

The cpu miner backend uses the wrong ranges of nonces instead of using `[startNonce,startNonce + nonce_chunk)`
(startNonce,startNonce + nonce_chunk]` is used. This will results in an overlap with nonces used by the gpu back-ends.

Add warning and fallback when auto intensity is 0

reduce memory usage for low end gpus

Fixed Minor Typo

Optimize Skein

Added/Rewrote instructions on how to compile in Windows; Fixed some typos and syntax; Added build option section

revert the change that the OpenCl function `rotate` is used instead of `SKEIN_ROT`