* [ fix ] Fix returned status of the `system` function
* [ re #238 ] Fix program error condition of `git diff` call in `Golden`
According to documentation, not only negative exit code means error
`testInDir dir ...` lists all directories in `dir` which contains
`run` files, and such directories are considered tests.
This is done to make test addition/maintenance cheaper.
Convert some test directories to `testInDir`, but not all of them
because
* some directories are listed in several test groups
* other directories are have some tests disabled
* Add trailing newline on non-empty list in unlines
There are several reasons to do that:
* a line in a text file is something which ends with newline,
and the last line is not special
* `unlines []` should be different from `unlines [""]`
* `unlines (a ++ b) = unlines a ++ unlines b`
* Haskell does it
* Change lines function behaviour
Situation I just ran into that I found confusing:
```
Golden value differs from actual value.
Accept actual value as new golden value? [y/N]
N
Invalid answer.
```
Put the dependency checks in the banner, e.g.:
------------------------------------------------------------------------
Base library
✓ Found Chez at /usr/bin/chezscheme9.5
✓ Found node at /usr/bin/node
------------------------------------------------------------------------
* Banners for test pools
* Summary with the list of failing tests at the end
* Option to write the list of failing tests to a file
* Option to read the list of tests to run from a file
* Using these two latest features to add a new make target to rerun precisely the tests that failed last time
