BString: Add SetToFormatVarArgs()
copyattr: Fix error output
BPackageResolvableExpression: Add Matches()

Checks if the given BPackageResolvable respectively the BPackageVersion
pair satisfies the expression.
BPackageInfo: Add Matches()

Checks whether the package satisfies the given
BPackageResolvableExpression.
Add private storage kit class BCopyEngine

It provides the functionality to copy file system entries (also
recursively). The code originates from the copyattr sources. Some
copyattr specific functionality has been removed and the code has been
adjusted for library use (i.e. no exit()s or fprintf()s). An optional
controller object can be set to customize the behavior.
pkgman install: Add base package support

If any of the packages to install has requires a base package, that is
installed in a more general installation location, we copy the package
to the target installation location. Ideally we'd hard-link, but BFS
doesn't support that. Symlinks would be a small nightmare to maintain.

We might want to choose the installation location intelligently
depending on the base package requirement -- e.g. install curl_devel in
system rather than common, since curl is installed in system -- so we
can avoid duplicating packages.
Enable -Werror for package_repo and pkgman
rule ArchitectureSetup: Remove superfluous arch macro definition

The macro for the architecture is already defined by the compiler.