Consider allowing capital internal vars ($ARGS, $DEPS, etc)

[DannyBen]

Description

As discussed in #581, perhaps we can:

1. Have a capital_global_vars setting
2. When it is true, add a declare -gn ARGS=args DEPS=deps to enable both capital and lowercase vars

Another option is to have more flexibility with this kind of settings scheme:

args_varname=ARGS
deps_varname=DEPENDENCIES
other_args_varname=EXTRAS

[DannyBen]

@meleu - this feature is implemented in #587 with a slightly different settings syntax.
I think this works well.

Next - I want to move all the declare from run() to initialize().

[DannyBen]

This is ready to be tested if interested.

[meleu]

Yeah, it works beautifully!

[DannyBen]

Alright - so we can close this I guess, and I will probably release tomorrow.