Remove '-e' from help.

Feature removed in 5d1c600279f6c9878aeb1194fc72088638a4362d
Move IsTrue and IsFalse near other helper functions
Normalize date with sh instead of sed

Removes a subshell and sed call per snapshot checked (on Linux and
Solaris).

Normalizing is now ~30 times faster.
Now completely sed-free
Re-add SkipPool check to destroy.sh

Got lost in the migration to one script per command
Check SkipPool /after/ FSExists in snapshot.sh

This helps testing scripts even when scrubs are running