.editorconfig: Automatically configure multiple text editors

See editorconfig.org for details of the format. This is a first attempt
at describing our coding style in editorconfig syntax; please add new
file types here as they become relevant.

Signed-off-by: Simon McVittie <smcv@collabora.com>
19 jobs for editorconfig in 29 minutes and 49 seconds (queued for 2 seconds)