Add complete bibliography as standalone document

For convenience, this commit adds a complete bibliography that compiles
to its own pdf file.  This lets teachers, etc., display one copy of the
backmatter for all of the separate parts.
Merge branch 'master' into edit-asymptotics-text
Version 0.3.4, edits to inference material and reorganiziation

This commit edits several parts of the inference material and makes
many internal changes that should make organizing and compiling the
files easier.  It also renames the book to be *Core Econometrics
Textbook*.
Merge tag 'v0.3.4'
Merge branch 'master' into edit-asymptotics-text