add support for new "pretend" option. familiar to gentoo users, this option "pretends" to download and instead returns a list of packages that would be downloaded.
add support for new "pretend" option. familiar to gentoo users, this
option "pretends" to download and instead returns a list of packages
that would be downloaded.

Also, fix a bug with pushErrorHandling() that was not setting things
properly if a local file had a package.xml problem


marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core