Switch to snake_case

[splatteredbits]

Rename all tasks to snake_case. Add backwards-compatible aliases.

To add support for properties, pass property names as-is to any TaskParameter hashtables. Convert any snake_case properties to SnakeCase and check if the function has a parameter with that name. If it does, pass the property value to that parameter.

Allow support for built-in properties to be passed either CamelCase or snake_case.

Should we warn if someone uses CamelCase?

[splatteredbits]

Started work on the feature/snake_case branch. More involved than I thought.