Should fix#34, when NVIDIA card provides memory type with several
addional flags more than code has asked but retuns error on allocate.
Code has be changed to use first memory type with minimal prefered
properties.
E.g. if code needs VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, a first block should be used
instead a fourth as before:
```
Memory blocks:
1: VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT
2: VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT VK_MEMORY_PROPERTY_HOST_COHERENT_BIT
3: VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT VK_MEMORY_PROPERTY_HOST_COHERENT_BIT VK_MEMORY_PROPERTY_HOST_CACHED_BIT
4: VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT VK_MEMORY_PROPERTY_HOST_COHERENT_BIT
```
This was first developed in a feature branch in the main yquake2 repo.
It was merged into master in early 2021, but the experiences of the
following month showed that it is not ready for prime time. There're
glitches with 3rd party assets, restarts are still shaky, etc. Having
the code in a separate repo allows us to:
* Release Vulkan independent if YQ2.
* Give commit access to contributors interested in Vulkan.
This code is the same as in yquake/yquake2 ecdf912713eef55d6c5d5a772259b44e3fc232c4.
