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

There are a lot of hiccups on this step in the AEON Slack Channel.

Fix for #750, #626, #606, #534, without having to downgrade and do not require modification of host_config.h
Require an additional component during VS2017 installation (VC++ 2017 version 15.4 v14.11 toolset) and an additional command execution before compilation.

Only install if the user doesnt already have the packages installed, no
point in reinstalling everything.

* compile howto on amd mac

tested on the latest 15" MacBook Pro

* Add a note about OpenCL/Xcode

Changed capitalization of "macOS"

Squashed the commit

it's not installed in ubuntu by default.

I removed typos, changed the wording and made the whole thing more noob-friendly.

fix minor spelling error

Link windows to anchor

I ran into a problem following these instructions, and this change got me past it.

The command in question enables access to the C++ compiler (puts it on the PATH or something like that).  If you do it with `sudo`, it leaves you at a root shell prompt.  If you then exit that root prompt, to go back to non-root, then g++ is no longer accessible.  If you want to compile as non-root, then you need to do `scl` as non-root.

- add separate file for developer pgp key's

That's what it's called now: https://i.imgur.com/juZhtyz.png

I chuckled reading that my virus protection software might flag the miner binary as “male ware,” and rewrote that section of the documentation.

- remove CMake option `WIN_UAC`
- spawn UAC dialog via restarting xmr-miner with administrator right
- allow to disable UAC with `--noUAC`
- update documentation
- remove usage section with help message (output depends on OS)

I expect that link is something that would be easily lost if another item is added.

Change the default for strided index. Th euser feedback shows that strided_index = true will give a view hashes more per second.

Allow to change the indexing used to address the hash scratchpad memory.

- add option `strided_index` for each gpu

- add documentation
- add environment variable `XMRSTAK_NOWAIT`

add warning that portable binaries are experimental

add hint that the new compiled xmr-stak-dep must be used for the new VS tool chain

add NVIDIA cli options to the help message

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

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

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

rename to make it clearer that this is a linux binary

- 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

Documentation: Add environment variables to increase OpenCL memory pool

- update usage.md
- hpdate help output

- fix wrong text box

- add CMake flag `XMRSTAK_COMPILE` to select `native` or `static` compile
- add new flags to the documentation