Git 2.13.0 RC1

This is the first preview using Git 2.13.0. Git LFS has also been updated to 2.1.0.

• Git release notes
• Git for Windows release notes
• Git LFS release notes

File	SHA256 checksum
dugite-native-v2.13.0-macOS-183.tar.gz	57097ba2fb9cec82113666c63950879abf9dccf326c3edeb760ae7b90a5fceb5
dugite-native-v2.13.0-ubuntu-183.tar.gz	9ea72f549511b48d6a32d46bcf1cbbbb25cca180b160f5ae42597eb2a19622fc
dugite-native-v2.13.0-win32-183.tar.gz	eeae82ee7f65442f54b180769dac3ee590b0fa36332cf538d47484351493c25c