editorconfig: add initial file
Our files roughly fall into the following groups:
- source code - c/c++/cocoa - 4 spaces indent
- meson - 2 spaces
- cmake - 2 spaces
- android build - mix of tabs and 4 spaces -- on their way out
- handwritten Docbook XML files (ouch) - 2 spaces
- various one-off files
Based on the above - let's add editorconfig file for meson and "everything else". It's a decent start going forward.
Signed-off-by: Emil Velikov emil.l.velikov@gmail.com