Add asplode support for :rename option in :require libspecs

Since both `require` and `use` both call `load-lib` internally, both
functions can also be supplied a :rename option.
Add :rename failure type to regrow

If an old ns contains a :rename entry for a missing refer, we attempt
this rename before any others.

If the old ns does not contain a possible :rename entry, the :rename
path is __NEVER__ attempted since a missing reference could be
hypothesized to be a rename of ANY public var.

slam.hound.regrow/candidate has been made private as the function
signature has changed, decreasing its suitability for public
consumption.
Merge branch 'rename-support'

Closes #68

* rename-support:
  Add :rename failure type to regrow
  Add asplode support for :rename option in :require libspecs
Release 1.5.3