Merge pull request #2 from leomuona/master

Adding and tweaking conceptual design. TODO: project timetable and additional info
Design sketch, and some text to make sense of it.
Merge pull request #3 from jesseniemisto/master

Design sketch, and some text to make sense of it.
Specified audio amplifier chip.
Merge pull request #4 from jesseniemisto/master

Specified audio amplifier chip.
Timetable written