RepoConfigLoader: don't use ValueError to warn

Handling ValueError can hide tracebacks from unexpected bugs,
so avoid it.
Add man/ru/color.map.5
RepoConfigLoader: fix bug #474578
Improve portage.repository.config.RepoConfig.__repr__() for location of DEFAULT repository.
portage.repository.config.RepoConfigLoader: Add __setitem__() and __delitem__().
portage.package.ebuild.config.config(): Add repositories parametre.
repoman: re-use repoman_settings.repositories

This avoids constructing a separate instance for each profile.
portage.repository.config.RepoConfigLoader: Fix __delitem__() and unimplement __setitem__().
portage.repository.config.RepoConfigLoader: Add __contains__().
portage.repository.config.RepoConfigLoader: Support io.StringIO in paths argument.
Stop setting PORTDIR / PORTDIR_OVERLAY in repoman.
repoman: samefile for repo location comparison

This ensures correct behavior with symlinks.
repoman: dedent generated repos.conf

This fixes a "File contains no section headers" error raised by
configparser with Python 2.