Instead of a stub

Platform argument didn't worked with custom deployment target

All those which contain nested git repos should have all changes committed.

Which brings proper scoping for libraries and frameworks as well.

Edit: Turns out that even though that's true for Xcode in isolation,
this was actually a misconception for CocoaPods. Both build product
types need different auxiliary files and some components of the
installer (e.g. `PodSourceInstaller`) are not ready for such usage.
I decided that the possible win having files de-duplicated across
targets doesn't outweight the added complexity.

This strategy further differs from what Xcode does and breaks native copy files build phases, but allows complete deduplication. It excludes with the new scoping any name clashes where a pod depends on others, which are built in multiple variants, so that it wouldn't be possible without that to add them to the framework search paths, so that just the right variants of each is visible.

… and error-prone by avoiding spaces in target labels, which are used to compose file paths.

e.g. if a pod is used on multiple platforms but on some more than once,
also if different targets depend on different subspecs sets of the same
pod and in cases where both combined is necessary.

[Gemspec] Bump Molinillo to `~> 0.4.3`

[ErrorReport] Clean up generation of stack section