Merge branch 'ps/cat-file-null-output'

"git cat-file --batch" and friends learned "-Z" that uses NUL delimiter for both input and output. * ps/cat-file-null-output: cat-file: add option '-Z' that delimits input and output with NUL cat-file: simplify reading from standard input strbuf: provide CRLF-aware helper to read until a specified delimiter t1006: modernize test style to use `test_cmp` t1006: don't strip timestamps from expected results