Updates for newer compiler versions

1. [VS2022] Include <utility> to get std::cmp_less_equal() compiled.
2. [Standard] Re-implement bux::C_ScreenerNo in a more compliant way.

Accumulated updates

1. [New] C_UnicodeIn::encoding()
2. [Change] Pass std::basic_string_view<T> arguments by value, not by reference, to one of overloaded ctors of bux::C_MBCStr
3. [Change] Rehaul bux::fittestType() in C++20 - concept lite & if constexpr
4. [Change] Add code page 951 (Big5 with HKSCS-2001) as one of encoding candidates to test in C_UnicodeIn
5. [Change] Forbid r-value string instance as ctor parameter of bux::C_IMemStreamT<>

Misc improvements with minor breakage of includes

1. [Change] Move HRTN() & OXCPT() from LogStream.h to StrUtil.h.
2. [Change] Rewrite I/O manipulator bux::timestamp utilizing fmt::format() to shorten the boilerplate code.
3. [Change] Quit assuming std::string::begin() is defined as const char * upon implementing ctor of bux::C_IMemBuf.
4. [Change] Harden the criteria to make flag values prefixed with '-' (negative numbers) hardly missed (i.e. misunderstood as short-named flags).
5. [Change] Claim that "Behavior of adding duplicate subcommands or flags of the same name is undefined." i.e it is caller's responsibility.
6. [Change] No more prepend ./ to the command name of USAGE part of help text.
7. [Change] Allow bux::scanFile() to provide encoding code of the input stream. The change of function prototype has a virtue of preventing short strings from guessing the wrong encoding.
8. [Bug] C_ScannerImpl<>::add() may throw due to losing its track of the last non-null action function pointer.
9. [Change] Were C_ScannerImpl<>::add() thrown, the incorporated message will have value of m_CurState.

Bug/quirk fixes & enhancements

1. [Bug] C_EZArgs::parse() misunderstands negative numbers as flag short names.
2. [Dependency] Update according to issue #4 related to vcpkg build.
3. [Quirk] C_EZArgs::help_full(): Keep "USAGE:" a empty line away from "DESCRIPTION:"
4. [Obsolete] Remove ParaUtil.h(bux::C_NumIter<>) due to deprecation of std::iterator<>
5. [Change] Parameters trigger & parse of all C_EZArgs::add_flag() overloads now passed by rvalue references for better performance.
6. [Change] Loose the container parameter type requirements of C_PathFmtLogSnap::configPath(uintmax_t fsize_in_bytes, const auto &fallbackPaths)
7. [Change] Replace DEF_CONFIGURABLE_LOGGER_FILES with DEF_FALLBACKABLE_LOGGER_FILES(first,...) to initialize the global logger in place.
8. [New] test/archlinux/README.md to remind myself.

Downgrade -std=c++20 flag to -std=c++2a to allow vcpkg triplet x64-linux to pass

1.6.3

Downgrade -std flag to let vcpkg triplet x64-linux to pass

[bugfix] No such operator from standard: std::string += std::filesystem::path

Full Changelog: 1.6.1...1.6.2

Conceptualize bux::C_EZArgs

1. [Change] We now have 9 C_EZArgs::add_flag() overloads.
2. [Change] Must provide onParsed parameter when calling C_EZArgs::add_subcommand()
3. [Change] FUNLOG() now logs function name only (FUNCTION) instead of full function signature (FUNCSIG) to avoid logging
   convoluted long names.

EZArgs.h conceptualized

1. [Change] bux::C_EZArgs methods conceptualized.
2. [Change][Incompatible] bux::C_ErrorOrIndex knows the difference between error and help text.
3. [Change] Argument dirs of bux::search_dirs() is now typed as std::ranges::forward_range instead of in-house bux::ConstPathList
4. [Change] const std::string & is somtimes more efficient than std::string_view
5. [Change] Methods of bux::C_EZArgs tuned for uint tests to pass. But the changes are also healthier and more tolerable in the long run.
6. [New] RAW_LOGIC_ERROR(), RAW_RUNTIME_ERROR() with no source trace, just the formatted message.

p.s. This release id not for clang, which is lack of C++20 P0634R3 feature.

bux::C_ParaLog is ready for use

1. [New] bux::C_ParaLog is ready for a variety of parallel logging configurations, filtered or unfiltered.
2. [New] Necessary helper classes for implementation s.t logger users no longer need to declare child source instances explicitly.
3. [New] Add methods to ParaLog.h & SyncLog.h to support testability.
4. [New] Add unit test cases to ParaLog.h & SyncLog.h (test_paralog & test_logger)
5. [New] Update what are found in test/ to test/archlinux/aur_poc/
6. [Bug] std::uniform_int_distribution<unsigned char> no longer allowed.
7. [Change] CUR_FUNC_ for Windows (MSVC)
8. [Change] tbb is no longer implicitly needed by C++ standard library.
9. [Change] smoke_filtlog.cpp verifies 2-level log filters ok.

SCOPELOG() indentation & new macro LOG_RAW()

1. [Bug] Boudary lines of SCOPELOG() & SCOPELOGX(), and so FUNLOG & FUNLOGX(), are indented deeper in the same depth with scoped log lines.
2. [New] LOG_RAW() simply logs what is formatted by arguments between ( ) without the ordinary timestamp-tid-loglevel prefix.