Allow specification of module dependencies for appups

[rnewson]

The order in which modules, within an application, are loaded can be
important. This patch adds allows the specification of module
dependencies such that generate .appup/.relup scripts will load a
module's dependent modules before itself.

To use:

in rebar.config, add a module_deps

{module_deps, [{ModuleName, [DependentModuleName, ...]}]}.

ModuleName is the name of any module, followed by a list of module
names that it depends on.

[ghost]

@joewilliams?

[joewilliams]

+1

[rnewson]

I'm going to enhance this a little. appup generation fails if one of the module dependencies isn't being updated, which makes managing the {module_deps ...} tuple rather onerous. Instead, I'll filter out the dependencies that aren't changing, then the module_deps list is more static, changing only when new modules are created. Won't take long.

[rnewson]

There.

[joewilliams]

Thanks @rnewson this seems like a good patch.

[rnewson]

cheers, certainly seems to do the trick for me. Is it tidy enough for your tastes? e.g, https://github.com/rebar/rebar/pull/139/files#L0R155

[joewilliams]

Yeah, a little funky but works for me. Thanks man.

[jaredmorrow]

@joewilliams knows more about app ups than anyone else, so that's good enough for me.