Merge commit 'sg/merge-options^' into jk/renamelimit

* commit 'sg/merge-options^':
merge, pull: add '--(no-)log' command line option
fmt-merge-msg: add '--(no-)log' options and 'merge.log' config variable
add 'merge.stat' config variable
merge, pull: introduce '--(no-)stat' option
doc: moved merge.* config variables into separate merge-config.txt

diff --cc Documentation/config.txt
Simple merge

diff --cc builtin-fmt-merge-msg.c
Simple merge

diff --cc contrib/completion/git-completion.bash
Simple merge