[Specs] [Pod::UI] First set of unit specs
[UI] Adapt to the removal of the Set::Statistics class
[PodTarget][Migrator] Store private headers in Pod/Headers/Private instead of Build/

Just in case SCM decides to ignore build directories
[CHANGELOG] Add entry for moving private pod headers
Merge pull request #2911 from CocoaPods/seg-store-build-headers-in-private

[PodTarget][Migrator] Store private headers in Pod/Headers/Private instead of Build/
[IntegrationSpecs] Update for move of private headers

Followup to https://github.com/CocoaPods/CocoaPods/pull/2911
[SpecHelper] Consolidate pre-flight setup code
Merge pull request #2845 from CocoaPods/issue/2845

[Unit Tests] Add specs for `Pod::UI`
[Gemfile] Point to Core from master
Merge pull request #2903 from CocoaPods/seg-delete-statistics

[UI] Adapt to the removal of the Set::Statistics class
Validate that a specification's `public_header_files` and `private_header_files` file patterns only match header files.
Also, validate that all file patterns, if given, match at least one file.
Merge pull request #2917 from CocoaPods/seg-validate-file-patterns

Validate that a specification's `public_header_files` and `private_header_files` file patterns only match header files.
Add support for swift source files
[Doc] Add group for better separation
[Doc] Add some method-inline comments
[Spec][Fixtures] Add a Swift podspec fixture

Never compare that to banana-lib!
Add methods to check if a target uses swift
Support framework as type for generated target
Integrate product_refs of generated frameworks
Migrate from static library to framework