add (-P | --perl-regexp) option
rename patterns.bats to extended_patterns.bats
extract unrelated tests from extended_patterns.bats
add explicit [-E | --extended-regexp] option

Currently it's the default.
remove shell metacharacter test
fix test name
git-substitute version 1.4.0

  - add [-P | --perl-regexp] option
  - add [-E | --extended-regexp] option