Log Message:
libass: updated to 0.17.0

libass (0.17.0)
* Fix various parts relating to automatic linebreaking
* Fix rendering when hinting was enabled and fontsizes or scales are zero
* Switch build to a non-recursive setup for improved parallelism
* Improve quality of SSA Effects movement
* Further documentation improvements
* Completely invalid Events are now discarded during parsing

* Introduction of LayoutRes{X,Y} script headers
* New AlphaLevel style override to set all alpha values while keeping the color
* Add ASS_FEATURE_WRAP_UNICODE to allow automatic linebreaks in accordance
  with the Unicode line breaking algorithm instead of ASS' much stricter
  breaking rules. For the feature to be available at runtime, libass must be
  linked against the new optional dependency libunibreak.

* Improve VSFilter compatibility:
  * Fix premature truncation of animated alphas (was a 0.15.0 regression)
  * Fix handling of small delay parameters for legacy SSA Effects
  * Fix x-scaling with PlayResX
  * Fix x-scaling for anamorphic video
    (except for \be whose scaling remains buggy in general)
  * Support SSA's AlphaLevel style field
  * Support the \kt override tag from VSFilter's v4++ set
  * Parse ScriptType headers
  * Parse integer header, style and event field values like VSFilter
  * Ignore trailing whitespace in an event's text