Cmakeutils

* allow cmake_compile to build with all CPU if system has enough RAM
* -workdir option allows using own development branch of CMake

* use entry_points since that's much more convenient for day-to-day use than a script laying around somewhere
* cmake_compile: use tempdir and modern CMake command syntax

use .zip file for Windows binaries to allow multiple Windows CMake installs, which is not possible with the .msi installer. The .zip method is much faster and automated vs. .msi.

Deduplicated and made cmake_setup more robust, for example checking that requested version is available rather than giving HTTPerror

* python ninja_setup.py download and installs the latest Ninja release. Ninja is highly recommended to use with CMake on Windows, Mac and Linux.
* increase CI coverage

* cmake >= 3.14 required to make life easier for the modern CMake user
* noted how BUILD_BYPRODUCTS is necessary for CMake ExternalProject with Ninja
* added cmake_compile.py for those needing to build CMake from source e.g. on ARM
* cleaned up all example CMake scripts