Authentic ping, fix re-evaluation issue

This release:

• fixes a re-evaluation issue that caused an infinite loop on mode reactivation (by @csanchezdll, fixing #19 and #23)
• adds a proper, authentic ping (by @joeheyming, fixing #10)

Version bump to align tag and internal version

v1.4.1

Merge branch 'develop'

New multiple sound mechanism, internal improvements

v1.4

Merge branch 'develop'

Distinct sounds

v1.2

Indentation fixes

Audio feedback for mode toggle, minor improvements

Merge pull request #5 from rbanffy/develop

README improvements

Works as expected

Makes a nice Selectric sound, both on Ubuntu an on OSX.