1) Remove 'video' impex plugin. Now the exporting classes are built in
   into animationrenderer plugin. It allows us not to pass the options
   via untyped KisPropertiesConfiguration, but via a type-safe and
   compiler-tracked KisAnimationRenderingOptions.

2) Add options for configuring HDR video encoding with HEVC (H265) codec

3) When HDR video option is activated, then PNG export filter is automatically
   forced to output HDR PNG files (see a hack in DlgAnimationRenderer::
   getFrameExportFilterConfiguration())

4) !!! Rendering dialog now supports relative paths for video and frame
   export locations. As a base it uses either document location, or the
   location of animation/frames, if it is present and absolute.