Use correct path for import in umbrella header when preserving header_mappings_dir

Prevent installer to be run from inside sandbox directory

Add spec for using relative paths inside the header_mappings_dir
if specified for umbrella header generation.

When preserving the directory structure inside a projects header_mappings_dir,
the file structure also needs to be taken into account when generating the
umbrella header for the Pod target.

Instead of the basename, use the relative path in the header_mappings_dir, if
one is set for the Pod.

Remove newline causing color problem when printing to a pager

Track .def files as sources

Improve sorting algorithm for `pod search`

[Installer] Adding sandbox to PostInstallHooksContext

[PodTargetInstaller] Set deployment target for resource bundle targets

[PodTargetInstaller] Set deployment target to maximum spec deployment…

[AbstractExternalSource] Quickly validate specs