Vulkan example: Fix validation layer warnings and errors and redeclare gl_PerVertex.

Examples: Vulkan: Shallow stylistic changes (following #879)

Add location decorators & change to use structs as in/out in glsl, update embedded spv (produced with glslangValidator -x)

Null the released resources

Added a void* user_data parameter to Clipboard function handlers. (#875)

Examples: Accessing ImVector fields directly, feel less stl-ey and fix renderer side assert when render list only contains a callback (#810)

Fix Vulkan example for use when a depth buffer is active.

tabs to space, remove braces

maxImageCount may be 0; add missing sType; change to 1 push constant range

Examples: Vulkan: Coding style tweaks.

Vulkan Example: Some code layout changes.

Vulkan Example: Fix synchronization.

Vulkan example.