contrib: remove editorconfig

This file was added in 962f347923, at which
time there already were doubts about it being useful. For Go, `gofmt`
already dictates formatting (and proper editors would integrat with
that). For other languages, most editors would already have a config,
and our CI validates formatting for various files.

Give that the file was never updated since it was added, it's fair
to say that it's unmaintained. Let's remove.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

contrib/editorconfig

@@ -1,13 +0,0 @@
-root = true
-
-[*]
-end_of_line = lf
-insert_final_newline = true
-charset = utf-8
-indent_style = tab
-indent_size = 4
-trim_trailing_whitespace = true
-
-[*.md]
-indent_size = 2
-indent_style = space