change lib/ to libexec/

fixes Homebrew/homebrew-core#3663 (comment)

.travis.yml

@@ -33,4 +33,4 @@ install:
 script:
   - ./bats/bin/bats test/*.bats
   - shellcheck diff-so-fancy update-deps.sh
-  - perlcritic -1 -q --theme freenode lib/diff-so-fancy.pl
+  - perlcritic -1 -q --theme freenode libexec/diff-so-fancy.pl

diff-so-fancy

@@ -23,7 +23,7 @@ else
 fi
 
 print_header_clean () {
-  "$(get_script_dir)/lib/diff-so-fancy.pl"
+  "$(get_script_dir)/libexec/diff-so-fancy.pl"
 }
 
 # run it.

readme.md

@@ -62,10 +62,10 @@ If you want, you can choose to install manually:
 1. Grab the two scripts (`diff-highlight` and `diff-so-fancy`) via either downloading or cloning the repo.
 1. If you download `diff-highlight` from the official git repo, give it a `chmod +x`.
 1. Place them in a location that is in your `PATH` directly or with symlinks.
-1. Place `lib/diff-so-fancy.pl` in the same directory as `diff-so-fancy`. You will end up something like this:
+1. Place `libexec/diff-so-fancy.pl` in the same directory as `diff-so-fancy`. You will end up something like this:
    * `~/bin/diff-highlight`
    * `~/bin/diff-so-fancy`
-   * `~/bin/lib/diff-so-fancy.pl`
+   * `~/bin/libexec/diff-so-fancy.pl`
 1. Set up the git `core.pager` config, as described above.
 
 Note: The `diff-highlight` dependency is an [official git-contrib script](https://github.com/git/git/tree/master/contrib/diff-highlight), duplicated here for convenience. If you prefer less fancy in your diff, you also use diff-highlight [on it's own](https://news.ycombinator.com/item?id=11068436).