Factory classes - get type from peek at config file

[b-adkins]

Factory classes would now look for a "type: ClassName" YAML-esque field in config files. They would reset the file pointer and pass opened file to appropriate class's initializer.

loadFromFile(ifstream config)
or
loadFromFile(ifstream index)

Pros:

• Removes file opening boilerplate from loadFromFile methods
• Greatly reduces file extension clutter
• ClassName uniquely identifies class and is easy to autogenerate (no key:value needed)