publishCursor(): now it returns observer instead of pushing it to global array, this fixes one bug in updateChildren
tests/basic-joins: 'disabling 4..10' test was fixed; the rest was corrected to match order of elements in Minimongo
publishCursor() now returns object with 'observer', 'activeItems', and 'name' fields
updateChildren(): now it automatically removes all children during updates. 'removeAll' parameter was added; calls of updateChildren() were added to smartRemove