* 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
* Modernize bitfield.cc: Storage changed to vector of bytes, return vector from getRaw, new Span readonly memory view
Modernize bitfield.cc: Code style/review notes
Modernize bitfield.cc: Code format
* Modernize bitfield.cc: Swap end and begin in bit counting code assertion
* Modernize bitfield.cc: Rewrite states and simplify code
* Modernize bitfield.cc: Fixing the code and tests
* Modernize bitfield.cc: Fixing tests
* Modernize bitfield.cc: Formatting; +std::size, +const
* Modernize bitfield.cc: Grouped member functions into the struct; C++ construction
* Modernize bitfield.cc: Naming style similar to qt/ C++ source
* Modernize bitfield.cc: Bitfield test updated to new API
* Modernize bitfield.cc: Renames for private functions
* Modernize bitfield.cc: Formatting
* Modernize bitfield.cc: Remove struct in 'struct Bitfield' and update commented code too
Co-authored-by: Charles Kerr <charles@charleskerr.com>
