Returns an array of update preferences for the current package. This method
is used to ensure that users are not asked about updates they do not want
to be asked about.
The array returned may have up to four elements:
PEAR_PACKAGEUPDATE_PREF_NOUPDATES
if TRUE the user does not want to know about any new updates.
PEAR_PACKAGEUPDATE_PREF_NEXTRELEASE
if set, the user does not want to be asked until
a version greater than the value of this element has been released.
PEAR_PACKAGEUPDATE_PREF_TYPE
if set, the user does not want to be
notified unless the release is at least the given type (one of
PEAR_PACKAGEUPDATE_TYPE_BUG, PEAR_PACKAGEUPDATE_TYPE_MINOR,
PEAR_PACKAGEUPDATE_TYPE_MAJOR).
PEAR_PACKAGEUPDATE_PREF_STATE
if set, the user does not want to be
notified unless the release has at least the given state (one of
PEAR_PACKAGEUPDATE_PREF_STATE_DEVEL, PEAR_PACKAGEUPDATE_PREF_STATE_ALPHA,
PEAR_PACKAGEUPDATE_PREF_STATE_BETA,
PEAR_PACKAGEUPDATE_PREF_STATE_STABLE).