* refactor: make tr_block_info::init_sizes() private
* refactor: remove unuse tr_file_piece_map::empty()
* refactor: remove tr_file_priorities::reset()
* refactor: remove tr_files_wanted::reset()
* refactor: rename method to tr_file_piece_map::piece_span_for_file()
more consistent naming with tr_block_info
* refactor: rename method to tr_file_piece_map::file_span_for_piece()
more consistent naming with tr_block_info
* refactor: use standard class field order in tr_block_info
* refactor: move CompareToSpan from header to cc file
* refactor: make tr_file_piece_map::reset() private
* refactor: rename method to tr_file_piece_map::file_count()
* refactor: rename method to tr_file_piece_map::byte_span_for_file()
* refactor: constify tr_block_info function args
* refactor: fix more signed vs unsigned
* test: improve coverage in tr_bitfield::raw()
* test: improve coverage in tr_bitfield::count()
* test: improve coverage for edge cases in tr_bitfield::setSpan()
* test: confirm that excess bits in setRaw() are set to zero
* fix: edge case of tr_block_info::initBlocks() where piece_size is 0
this should not happen in production, but cover it anyway