Add speech bubbles

Stylised speech bubbles, rendered using css.

TeacherOne{It's raining again}
TeacherTwo{But it is only March}
TeacherThree{Never mind, it's nearly Friday}
TeacherSpeak{It's your time you're wasting}
TeacherTip{Getting angry only wears you out}
PupilSpeak{Julia}{I totally get this now}
JustSpeak{Physics is not so hard}
WrongTrack{Mathematics is the language of physics}
RightLines{Physics makes the world go round}

Selection, parsed

Teacher: It's your time you're wasting

Teacher Tip: Getting angry only wears you out

Julia: I totally get this now

Physics is not so hard

Wrong Track: Mathematics is the language of physics

Right Lines: Physics makes the world go round