Merge branch 'ab/get-short-oid'

Merge branch 'ab/get-short-oid'

When a short hexadecimal string is used to name an object but there
are multiple objects that share the string as the prefix of their
names, the code lists these ambiguous candidates in a help message.
These object names are now sorted according to their types for
easier eyeballing.

* ab/get-short-oid:
  get_short_oid: sort ambiguous objects by type, then SHA-1
  sha1-name.c: move around the collect_ambiguous() function
  git-p4: change "commitish" typo to "committish"
  sha1-array.h: align function arguments
  sha1-name.c: remove stray newline