add git ignore

Author: cjld

.gitignore

@@ -0,0 +1,31 @@
+my
+.refresh
+.DS_Store
+__pycache__
+.ipynb_checkpoints/
+.vscode/
+__res/
+perf.data
+perf.data.old
+*.swp
+*.ipynb
+*.pdf
+*.zip
+*.tgz
+*.obj
+test.py
+extern/mkl/mkldnn_lnx*/*
+data/
+build/
+venv/
+*.md
+!*.src.md
+!README.md
+!README.cn.md
+!CHANGELOG.md
+python/jittor.egg-info
+python/jtorch.egg-info
+dist/
+!doc/source/*
+core
+__data__