Add .editorconfig

# SPDX-FileCopyrightText: 2022 CERN and the Allpix Squared authors

# SPDX-License-Identifier: CC0-1.0

root = true

[*]

end_of_line = lf

charset = utf-8

trim_trailing_whitespace = true

insert_final_newline = true

[*.{h,hpp,cpp,tpp,C,py}]

indent_style = space

indent_size = 4

[*.md]

trim_trailing_whitespace = false