Log Message:
(devel/R-evaluate) Updated 0.14 to 0.15

Version 0.15
================================================================================
- `new_output_handler()` gains a `calling_handlers` argument. These
  are passed to `withCallingHandlers()` before `evaluate()` captures
  any conditions.

- Fixed #106: do not assume that `is.atomic(NULL)` returns `TRUE`
  (thanks, @mmaechler).