Log Message:
tex-unicode-math{,-doc}: update to 0.8n

* Add note to readme that the `lm-math` package is required for minimal
  functionality.
* Spacing fixed for maths fonts loaded with the `Scale` fontspec feature
* Commands like `\crampedtextstyle` now longer lead to an infinite loop
  under XeTeX.
* Improvements to the functionality of the test suite. (Although more
  tests would be nice.)
* Test suite is now (successfully) run with `expl3` debug mode enabled.