Updated imports to use nondeprecated libraries

pdf/build_book.bat

@@ -1,5 +1,5 @@
 ipython merge_book.py
 
-ipython nbconvert --to latex --template book book.ipynb
+jupyter nbconvert --to latex --template book book.ipynb
 ipython to_pdf.py
 move /Y book.pdf ../Kalman_and_Bayesian_Filters_in_Python.pdf

pdf/formatting.py

@@ -1,6 +1,6 @@
 from __future__ import print_function
 import io
-import IPython.nbformat as nbformat
+import nbformat
 import sys