Add an .editorconfig; document git whitespace settings

Most of the projects I work on don't use tabs, and while authoring my
first patch I had to wrestle with my editor to not introduce
whitespace editors.

The `.editorconfig` file is supported by a large number of editors
out of the box, and many more with plugins.

As a first-time contributor, I can't say for certain these settings
are totally correct, but thus far git and my editor are satisfied
enough.

I considered adding `git config --local format.signOff true` but
wanted to respect the warning:

    format.signOff
        A boolean value which lets you enable the -s/--signoff
        option of format-patch by default.  Note: Adding the
        Signed-off-by: line to a patch should be a conscious act and
        means that you certify you have the rights to submit this
        work under the same open source license. Please see the
        SubmittingPatches document for further discussion.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Graham Christensen <[email protected]>
Closes #9892 

1 files changed, 10 insertions, 0 deletions

diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 000000000..0f4b96a83
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,10 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{c,h}]
+tab_width = 8
+indent_style = tab