Added ignore of .bak files

.gitignore

@@ -1,64 +1,5 @@
-# test document not for distribution
+*.bak
+.ipynb_checkpoints
+__pycache__
+*.pyc
 short.pdf
-10_Unscented_Kalman_Filter_.ipynb
-tmp.ipynb
-Kalman_and_Bayesian_Filters_in_Python_files/
-
-# Byte-compiled / optimized / DLL files
-__pycache__/
-*.py[cod]
-
-# C extensions
-*.so
-
-# Distribution / packaging
-.Python
-env/
-bin/
-build/
-develop-eggs/
-dist/
-eggs/
-lib/
-lib64/
-parts/
-sdist/
-var/
-*.egg-info/
-.installed.cfg
-*.egg
-.ipynb_checkpoints/
-
-# Installer logs
-pip-log.txt
-pip-delete-this-directory.txt
-
-# Unit test / coverage reports
-htmlcov/
-.tox/
-.coverage
-.cache
-nosetests.xml
-coverage.xml
-
-# Translations
-*.mo
-
-# Mr Developer
-.mr.developer.cfg
-.project
-.pydevproject
-
-# Rope
-.ropeproject
-
-# Django stuff:
-*.log
-*.pot
-
-# Sphinx documentation
-docs/_build/
-
-# back ups
-*.*~
-*.zedstate