Added `procure-sub-ns` and `shadow-procure-sub-ns`, which generalize `ns-get-name`, `ns-get-string`, `ns-shadow-name`, and `ns-shadow-string`.
Added `procure-sub-ns` and `shadow-procure-sub-ns`, which generalize `ns-get-name`, `ns-get-string`, `ns-shadow-name`, and `ns-shadow-string`.

rocketnia/era-cene,rocketnia/era-cene,era-platform/cene,era-platform/cene,era-platform/cene,rocketnia/era-cene