added templates for section overview html files
Fixed problems in issue Ali raised.
Revise 1.c.iii.
Add screenshots for five patches.
Setting up template folder for exercise web pages; adding first draft of Arduino overview; updates to circuits overview.
Adding first draft of relay driver notes.
Editing relay driver copy.
Add motor knob example.
Adding three more exercise notes, updating others.
Added link and comment about common-emitter topology.
PNP -> NPN transistor.
adding overview.html
overview additions
updated template file for overview.html
unit 2 and 3 folder reorganization

to match the syllabus
Adding first draft of voltage regulation exercise notes.
Adding 1.b.i.1 notes, revising 1.B overview.
Moving 1.b.i.1 to correct folder.
Updating the exercise and section overview templates.
Adding four more Arduino exercises, revising Arduino overview.