Update template system

[binford2k]

Adding a ticket so I don't keep forgetting to do this. We need presentation templating that's less terrible than the current setup. This will allow one to add full page styling or write headers and footers, for example.

• use less crappy template tag syntax
• add global presentation level template
• write better templating documentation

See #769 for an alternate implementation

[lpirl]

Awesome!
I'd strongly vote for reusing an existing, reasonably mature and established template engine.

[bparsia]

One problem that I'm facing with templates is that adding images seems to be impossible.

(My basic problem is that I need to add my university logo to the upper left corner of each slide and this has been an epic nightmare. I tried CSSing it but then I get overlap with content. I'm trying to template it and this happened. It's extremely frustrating. I've been at it for many hours for something that is basically trivial :()

I've tried:

 <img src="logo.png">
 <img src="image/logo.png">
 <img src="/image/logo.png">

in the template which yields:

http://localhost:9090/image//introduction/logo.png
http://localhost:9090/image//introduction/image/logo.png
http://localhost:9090/image///image/logo.png

respectively.

It feels like the first is what's supposed to work.