Allow for inclusion #3
Description
Add an "include" directive that allows for merging in other configuration files. For example, to have a common config, config for parts of the site, config with sensitive information (e.g., passwords), etc. that can be composed together.
Still need to think about exactly how the merging would happen (e.g., precedence rules), at what levels "include" would make sense, support for relative vs absolute paths, if we need to worry about cycles, etc.