Fixed and tested `dirname_real` function. Added `expec_return` test function.
Using library file name prefixed with `test_` for test files.
Use `--posix` (posix compliance mode) for bash. Make function names posix compliant.
Make function definition  compatible
Remove comments from loaded/cached library and module files.
Removed here-strings. Unsupported by busybox ash.
Switch to `/bin/sh` in shebang.