Merge pull request #28 from mspiegel/task-no-parent-dir

Recognition when the parent directory of a task has been deleted.
disable search for task view because it doesn't work properly (incorrectly inherits search values from top nav) and isn't really required anyway.
Hardening the skiplist iterator so that it will not enter an infinite loop if a page has been corrupted.
In pageDB testing adding check to ensure that pages remain in range.
Revert "Hardening the skiplist iterator so that it will not enter an infinite loop if a page has been corrupted."

This reverts commit 9e864f79126157fc3faf563af03322c987ca016f.
Addition of SkipListCache#locatePage(K, LockMode, boolean) method
that allows for fetching a page with the exact key value, instead of
the default floor key value. This feature is used by the skiplist
iterator to ensure that the iterator will not enter an infinite
loop in the presence of invalid nextFirstkey values.