* Bump API patch number and header version number to 60 for this update.
Github Issues:
* Document that <<queries-timestamps, Timestamp Queries>> can only be
meaningfully compared when they are written from the same queue (public
issue 216).
* Document that the `<extension>` tag `type` attribute is required for
non-disabled extensions (derived from, but does not close public issue
354).
* Clean up registry schema length attribute descriptions to be consistent
and correct (public issue 555).
Internal Issues:
* Replace as much of the hand-written extension appendix metadata as
possible with asciidoc includes generated from corresponding attributes
of +vk.xml+, and enhance the style guide to match. This avoids
inconsistencies between +vk.xml+ and the appendices, and produces a more
uniform style (internal issue 137).
* Remove the generated extDependency.{py,sh} files from the tree and
create them dynamically on demand instead, reducing merge conflicts
(internal issue 713).
* Add a prototype tool for generating in-place difference markup for
sections guarded by asciidoc conditionals, and new syntax for open
blocks to support it (internal issue 833).
* Remove unnecessary restriction of etext:*SYNC_FD_BIT_KHR external handle
types to the same physical device in the
slink:VkPhysicalDeviceIDPropertiesKHR,
flink:VkImportMemoryWin32HandleInfoKHR,
slink:VkImportFenceWin32HandleInfoKHR, slink:VkImportFenceFdInfoKHR,
slink:VkImportSemaphoreWin32HandleInfoKHR,
slink:VkImportSemaphoreFdInfoKHR
<<external-memory-handle-types-compatibility, External memory handle
types compatibility>>, <<external-semaphore-handle-types-compatibility,
External semaphore handle types compatibility>>, and
<<external-fence-handle-types-compatibility, External fence handle types
compatibility>> sections (internal issue 956).
Other Issues:
* Remove dependency of +VK_KHX_device_group+ on +VK_KHR_swapchain+ (there
is an interaction, but not a strict dependency), and add a new
`extension` attribute to the `<require` XML tag to allow classifying a
subset of interfaces of an extension as requiring another extension.
Update the registry schema and documentation accordingly.
New Extensions:
* `VK_AMD_shader_fragment_mask` (and related `GL_AMD_shader_fragment_mask`
GLSL extension)
* `VK_EXT_sample_locations`
* `VK_EXT_validation_cache`
* Bump API patch number and header version number to 57 for this update.
Github Issues:
* Fix error in description of ename:VK_FORMAT_ETC2_R8G8B8A8_SRGB_BLOCK
block size (public issue 342).
* Update documentation of ename:VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BIT
to explicitly mention both graphics and compute pipelines (public issue
525).
Internal Issues:
* Document that
slink:VkPhysicalDeviceLimits::pname:framebufferColorSampleCounts does
not cover integer formats (internal issue 550).
* Add a note under slink:VkImageViewCreateInfo describing how values meant
for one format can be sanitized when used via another format (internal
issue 927).
* Add valid usage statements to ftext:vkCmd* documenting that image
subresources used as attachments must not be accessed as non-attachments
in a render pass (internal issue 929).
* Remove obsolete 'validextensionstructs' attribute from +vk.xml+, the XML
schema, and the schema documentation (internal issue 946).
New Extensions:
* `VK_AMD_mixed_attachment_samples`
* `VK_EXT_post_depth_coverage`
* `VK_KHR_relaxed_block_layout`
* `VK_NV_depth_range_unrestricted`
