Deboostify Crow

[luca-schlecker]

This Pr removes Boost as a dependency and will instead rely on the standalone asio library.
CI now installs libasio-dev instead of libboost-all-dev and the documentation resembles that change. (Although the MacOS section could use a double-check, I have no such device on hand)

Proper testing necessary

Unittests are all passing but I think some real-life testing does no harm.

Removed Boost functions and types and their replacements:

• boost::lexical_cast becomes crow::utility::lexical_cast. Its implementation relies on std::stringstream for converting between types.
• boost::hash_combine is replaced by a private function. Its implementation idea stems from around the internet and can be found in multiple sources.
• boost::iequals is replaced by crow::utility::string_equals taking two mandatory std::string arguments and one optional bool controlling the case-sensitivity.
• boost::system::error_code is replaced by asio::error_code which is an alias for std::error_code.
• Every boost::asio:: function is replaced with their standalone asio:: counterpart.
• boost::array is replaced with std::array.
• boost::posix_time is replaced with a std::chrono equivalent.
• boost::*_comparable is dropped and the respective operators are implemented manually.
• boost::lexicographical_compare is replaced with std::lexicographical_compare.
• boost::optional is replaced with std::unique_ptr.
• boost::trim is replaced with crow::utility::trim.

Introduced functions (*explicitly* tested?):

• private void crow::ci_hash::hash_combine. (❌)
• private bool crow::json::detail::r_string::equals. (❌)
• Copy-constructor for crow::CookieParser::Cookie. (❌)
• bool crow::utility::string_equals (✅)
• T crow::utility::lexical_cast (✅)
• std::string crow::utility::trim (✅)

[The-EDev]

What I found are the comments below and the drone error:

2: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2: unittest is a Catch v2.13.8 host application.
2: Run with -? for options
2: 
2: -------------------------------------------------------------------------------
2: middleware_cookieparser_format
2: -------------------------------------------------------------------------------
2: /drone/src/tests/unittest.cpp:1667
2: ...............................................................................
2: 
2: /drone/src/tests/unittest.cpp:1713: FAILED:
2:   CHECK( s.find("Expires=Wed, 01 Nov 2000 23:59:59 GMT") != std::string::npos )
2: with expansion:
2:   18446744073709551615 (0xffffffffffffffff)
2:   !=
2:   18446744073709551615 (0xffffffffffffffff)

And It's not a dealbreaker but formatting .drone.yml is somewhat incorrect and qs_parse is somewhat problematic (because while formatting Crow I attempted to keep external libraries away from clang)

[luca-schlecker]

I'll have to look into that unittest again. Passing fine on my system.
Unfortunately, I had to make a change to query_string.h and in the process vscode auto-formatted everything according to Crow's guidelines. The yml files were also formatted on save, reversed that change though.

[The-EDev]

Aside from the comments, I couldn't find anything concerning from looking at the code. I'll do a few local tests (to see if it compiles with GCC 4.8 for example) and we'll see what to do from there :)