fix, PEBKAC, upon failure to open in test() return immediately

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, uninvent the custom errno passing to error()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'code/hygiene'

* code/hygiene:
  minor, uninvent the custom errno passing to error()
  fix, PEBKAC, upon failure to open in test() return immediately
minor, provide hxdiff(1) tool, hexdump two files, display the diff

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
fix, PEBKAC, only display ragged lines when not a already congruent to 16bytes

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, finish diff child in fini_diff() as init'ted by init_diff()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
hygiene, clean up headers

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
chore, remove debugging output

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, don't redir stdout in diff child

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
test, provide regression cases for hxdiff

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'feat/hxdiff'

* feat/hxdiff:
  test, provide regression cases for hxdiff
  minor, don't redir stdout in diff child
  chore, remove debugging output
  hygiene, clean up headers
  minor, finish diff child in fini_diff() as init'ted by init_diff()
  fix, PEBKAC, only display ragged lines when not a already congruent to 16bytes
  minor, provide hxdiff(1) tool, hexdump two files, display the diff