Add an editorconfig

Just set to the style already used in the code, 4 spaces.
Ref #32

I left remove trailing whitespace commented out since there's an insane ammount of trailing whitespace in the source code.
Any small edits were causing big diffs that removed the whitespace.

TODO: uncomment and remove all trailing whitespace across the codebase.

.editorconfig

@@ -0,0 +1,17 @@
+# EditorConfig is awesome: http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 4
+insert_final_newline = true
+# trim_trailing_whitespace = true
+
+# Ignore .md files, because 2 spaces at end-of-line has meaning
+[*.md]
+trim_trailing_whitespace = false

CHANGELOG.md

@@ -16,6 +16,7 @@ The format is based on [Keep a Changelog.](http://keepachangelog.com/en/1.0.0/)
 * `CreateRawTransaction` RPC
 * `GetUnconfirmedBalance` RPC
 * `DecodeScript` RPC
+* An `.editorconfig` file for easier editing.
 
 ### Changed