It's not possible to get full backtraces in these instances when an
error is signaled, and I think we should generate full backtraces when
debug-on-error is enabled as a general rule.
I had to make this change at one place to track down the root of problem
2 in #5200.
Add actions for both helm and ivy.
TODO:
- see TODO in function body
- replace SPC h d p (list all packages, use spacemacs describe when
it is a layer package, otherwise use vanilla describe).
This layer configures spacemacs to use the ivy/counsel/swiper family of
packages. Default completion is done with ivy. This is meant to replace
helm for those who want it.
