Add sourcemaps

[vrugtehagel]

Debugging component definitions is currently not very nice; browsers handle the anonymous functions a bit differently and it can be hard to figure out where an error came from.

Basically, Yozo needs sourcemaps. The lib builds will not get sourcemaps, because they need to be generated client-side.

[vrugtehagel]

Currently not looking to implement this, for two main reasons:

• Inline sourcemaps (i.e. data URLs) don't work in all browsers right now, and don't seem to be designed for systems that split a single source file into multiple generated files (though the latter is probably not too much of an issue)
• To implement them correctly, we'll need to parse the template manually, since the DOM parser doesn't retain data about where in the plain text source a certain element or attribute came from. This means the dev bundle needs to ship an entire HTML parser, which for now seems unreasonable.

Instead, for now, I'll add comments to the generated functions saying where they were generated from.