PEAR_PackageUpdate::setMinimumReleaseType -- 
   Sets the user's preference for asking about release types.
  
Description
   Sets the user's preference for asking about minimum release types.
  
Throws
   throws PEAR_PACKAGEUPDATE_ERROR_INVALIDTYPE,
   when invalid type of release is used (bug|minor|major).
  
Note
   since 0.4.0a1
  
This function can not be called
statically.
Return value
   boolean - TRUE if the preference was set properly, FALSE otherwise.