[WIP] changes for next release 3.10.5

[nlohmann]

This thread collects all changes made since the 3.10.4 (#3083) release.

Bug fixes

• Make sure <filesystem> is properly included as a lot of older compilers do not fully implement the C++17 standard with respect to std::filesystem. Thanks to @miikka75 for providing an important fix for Clang 9.
  • GCC 7.5.0 with --std=c++17: filesystem: No such file or directory #3090 Apple build failed with json/single_include/nlohmann/json.hpp:4384:57: 'path' is unavailable #3097 Add C++17 copies of the test binaries #3101 std::filesystem unavailable on macOS lower deployment targets #3156 #include <filesystem> doesn't work with gcc-7 when -std=c++17 is specified. #3203
• Fix compilation error with NVCC
  • ordered_json::reset() compile error with nvcc #3013
  • Fix compilation error with NVCC #3234

Improvements

• Add a parameter to the update function to recursively merge objects with common keys.
  • deep copy (or merge?) #3006 Add recursive update function #3069
• Extend std::hash and std::swap to work on any nlohmann::basic_json specializations rather than just nlohmann::json.
  • Extend std specializations #3121

Further Changes

CI

• Update CI to use Clang 14, GCC 6, and Clang-Tidy 14.
  • Update CI #3088
• Update cpplint
  • Update cpplint #3225
• Add build step for NVCC. By @ax3l.
  • Add build step for NVCC and fix a warning #3227
• Remove Travis CI
  • Drop Travis CI #3087
  • Remove Travis CI #3233

Warnings

• Fix a warning for shadowed variables. By @kernie.
  • Warning for shadowed variables #3188 Fix: Warning for shadowed variables (#3188) #3193
• Fix a warning on a pointless comparison. By @nickaein
  • Add build step for NVCC and fix a warning #3227
  • Compiler warning with Intel compiler, same as #755 #2712
  • Compiler warnings with NVCC 11.2 #2676
  • some static analysis warning at line 11317 #1390
  • Compiling with icpc #755

Documentation

• Overwork documentation
  • Consolidate documentation #3071
• Fix typos in operator[] documentation. By @axnsan12.
  • Fix typos in operator[] documentation #3102
• Add examples for parsing from iterator pair.
  • Add examples for parsing from iterator pair #3100
• Fix spellings in comments. By @axic.
  • Fix spelling #3125
• Fix typos in documentation. By @striezel.
  • fix typos in documentation #3140
• Correct parameter name in parse documentation. By @daniel-kun.
  • Docs: Update skip_comments to ignore_comments #3145
• Fix link to FAQ. By @Prince-Mendiratta.
  • Fix FAQ hyperlink typo in readme #3148