On appveyor we only cache the `vcpkg/installed` directory, so vcpkg
itself still needs to be pulled from git.
Also update vcpkg from git if it has already been cloned, and always
rebuild vcpkg itself.
Signed-off-by: Rafael Kitover <rkitover@gmail.com>
Replace the vcpkg code with a newer and better version. In this version
the `vcpkg` directory is on the same level as the source directory, so
that IntelliSense does not get confused scanning for files.
The cmake variable `VCPKG_TARGET_TRIPLET` is required to activate vcpkg
support, it must be set to e.g. `x64-windows` or `x86-windows`.
Update `CMakeSettings.json` for the new code for the GUI.
Fix a problem copying the `SDL2.dll` file to the binary directory.
Update `README.md` with commandline instructions.
Signed-off-by: Rafael Kitover <rkitover@gmail.com>
Rafael Kitover