Merge branch 'am/pathspec-from-file'

A few commands learned to take the pathspec from the standard input or a named file, instead of taking it as the command line arguments. * am/pathspec-from-file: commit: support the --pathspec-from-file option doc: commit: synchronize <pathspec> description reset: support the `--pathspec-from-file` option doc: reset: synchronize <pathspec> description pathspec: add new function to parse file parse-options.h: add new options `--pathspec-from-file`, `--pathspec-file-nul`