Add gitignore

.gitignore

+# ignore build and install directories
+build/
+bin/
+lib/
+obj/
+
+# root and data files do not belong into the repository
+*.root
+*.pdf
+*.log
+*.dat
+*.macro
+*.ps
+*.wrl
+*.png
+
+# ignore backup files of any sort of editor:
+~*
+*~
+.*
+\#*
+
+# ignore python byte code
+*.pyc
+
+# Ignore Doxygen's SQlite3 databases:
+*.db
+
+# Ignore ROOTs compiled macro objects
+*.d
+*.so
+*.pcm