Fix clippy::perf and most of clippy::nursery
Part of #7.
This MR fixes any lint in clippy::perf and clippy::nursery (without empty_line_after_doc_comments, option_if_let_else and string_lit_as_bytes):
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empty_line_after_doc_commentsbecause I do not know where the documentation refers. -
option_if_let_elseis a big change as it reveals some code smell and should be done last. -
string_lit_as_bytesshould be done in a specific MR aboutwrite!.