64bit support for the CMake build on Windows

Adds 64bit support for the CMake build on Windows. The information and tips everyone shared in #1218 (closed) have been most helpful. Libtool has been removed in favour of the compatibility header suggested by @Chiel92, with some minor changes. Most of the other required libraries could be retrieved from the PHP download site for both x86 and x64. This means that the old x86 dependencies are replaced with newer versions, and the versions for both x86 and x64 are the same. The dependencies are still stored in the submodule, and autodiscovery of the plugins (generating the config file) still works.

The Pango plugin has also been added to the CMake build, so PNG output is now possible with the new build (so also for 64bit Windows).