really fail to not overwrite keys when forging
Removed old privilege escalation model

This commit refactors the handling of password input by eliminating
all intermediary programs and relying only on ZSh, hence improving
overall security against rootkits and such.

Also the way sudo is used is now greatly simplified and there is no
privilege escalation at boot: sudo is executed inside Tomb by being
prefixed in front of those programs needing it.

All tests passed.
KDF key handling cleanup