[TASK] (issue14): replace echo by printf
Replace echo by printf at remaining locations, where echo is used with options (as could be located by git grep). Seitosh should now be clean with respect to shell usage. Citation from the POSIX manual for printf as a motivation for this set of changes: RATIONALE The printf utility was added to provide functionality that has histori- cally been provided by echo. However, due to irreconcilable differences in the various versions of echo extant, the version has few special features, leaving those to this new printf utility, which is based on one in the Ninth Edition system.