* version updates
- qt to 5.11.x
- openssl to 1.0.2o
- protobuf to 3.6
* undo protobuf change
* reapply with proper semver
* only qt latest
* combined env, protobuf 3.6
* slim build matrix config down
* fix env
* test
* fix env -eq
* test if script changes work
* /2
* enable cache again
* fix
* final
## Short roundup of the initial problem
It was mostly out of date because we have to manually update it with our current version number.
The use of that is suspect anyway, since it only displays in the appveyor build overview.
It also had a redundant info about the branch.
## What will change with this Pull Request?
- remove hard coded version number
- remove branch
- cleanup build trigger from [#3300](https://github.com/Cockatrice/Cockatrice/pull/3300/files#diff-11c909939117928998b102a1fff7d363)
- more readable style
## Screenshots
I did some tests, so don't be confused about the different styles displayed in the history:
<!-- simply drag & drop image files directly into this description! -->
* prevent unnecessarybuilds
* readd qt5 string
sadly this is needed as of now:
ff6b0f86ec/cockatrice/src/releasechannel.cpp (L59-L68)
* wrap asterisks
* fixed with validator
https://ci.appveyor.com/tools/validate-yaml
* complete link
* add helpful links
this should not trigger a appveyor build
* add space in readme
this should not trigger a appveyor build
* highlight c++ types
this should not trigger a appveyor build
* remove empty line
this should not trigger a appveyor build
* declutter dockerignore
this should not trigger a appveyor build
* Appveyor updates
Remove unused stuff (mysql, choco)
Use MSVC 2015
Upgrade Qt to 5.9, protobuf to 3.4.1
* stick qith qt 5.6 for winxp 32bit compatibility; zlib test
* Appveyor is using a randmon clone path for pulls, get it from an env variable
