Adds all the functionality described in the README in cl/4066.
This code is very closely related to //users/tazjin/russian/russian.el
Change-Id: I14f1052cebfbe4886e75e8efc730eacbf8773f29
Passively is a tool to help people learn information via Emacs,
designed for language learning.
As of this CL, the actual implementation still lives in
//users/tazjin/russian/russian.el but I am generalising it here.
Change-Id: Iac5a8cfc78415496637a7ba5ddc4c2a1aa6bee26