Loaders should use IoC instead of being constructed w source

[eeverman]

The current implementation requires special treatment of standard loaders and makes it difficult to have only a single non Std loader. With IoC all loaders can be added by instance.

[eeverman]

The context for this might be called RuntimeLoadEnvironment to represent the state of the environment from the perspective of the loaders. This would include the following:

• Env Vars
• Sys Props
• Main Args
• Fixed Values

The 1st three are canonical runtime environment, the last is part of the effective environment from the perspective of the Loaders.

The RuntimeLoadEnvironment would be passed to Loader.load(). Not all will need it, but its possible loaders other than the StdLoaders will need it - Perhaps a custom loader knows how to translate Env Vars in a way that the Std. one does not.

Along with this, all other configuration methods of loaders should probably move to the constructor. This will keep the logic short for constructing Loaders in the config so that hopefully it does not require individual methods to construct each one.

[eeverman]

Fixed by #708