Allow user to specify template

[pspeter3]

Essentially a command line option to specify which HTML template to use.

[danvk]

What's your use case here? There's also a JSON output format that you can feed into other visualizations.

[pspeter3]

My use case is just to apply some custom styling. I really like the tree visualization but want certain things to be highlighted. Perhaps I should use the JSON version and log it.

[danvk]

What would you like to highlight? There's a long-standing issue to use color but we've been unable to come to consensus on it. #21

[pspeter3]

Some of it is specific to our bundle, like where we vendor third party code, but other is anything greater than 1% or 256kb