fkYAML version 0.4.0

* added get_value_inplace() to basic_node

* updated API documentation contents

* fixed some typos in doc

* added link to the documentation page for get_value_inplace()

* fixed error in building test suite with older compilers

* added test case for get_value_inplace

* fixed issue reported from codacy

* updated mkdocs-material & mkdocs-git-revision-date-localized-plugin

* updated copyright year in the license files

* restructured document pages

* revised documentation contents in the API references section

* organized structure of documentation contents in the API references section

* added top page & reordered documentation pages in the API references section

* update workflow jobs for release artifacts

* change extension: tar.gz -> tgz

* do not create a temporal, redundant lexical_token object

* search plain scalar contents for flow indicators only within a flow context

* modified validation of scalar contents

* reduced redundant calls in lexer

* updated benchmark results

* fixed a clang-tidy error

* emit errors if ":" is missing after a mapping key

* generalized codes to move back to a parent node with target indentation

* disable clang-tidy check (bugprone-easily-swappable-parameters)

* added test cases & addressed coverage loss

* detect bad indentation at block mapping entries

* improved parse context management

* detect error on too much indented block sequence entries

* added test cases

* fixed clang-tidy error

* addressed coverage loss

* run amalgamation

* deleted unused lambda capture in the deserializer

* updated copyright year

* rename: test -> tests, tool -> tools

* moved files for documentation

* moved project documentation files to the .github directory

* fixed path for coverage

* fixed paths in the script files

* fixed paths for publishing documentation

* fixed filtering paths for workflow triggers

* updated path for the reuse tool

…appings in a correct way (#456)

* fix: Fixed a bug where serialize didn't write out empty vectors and mappings in a correct way. I have not added a test case, but I tested it in my code and it behaved as expected. Adding a test case at some point would be good.

* added test cases for serializing empty collection nodes

* modified serializer impl to address coverage loss

* allow access to iterator member functions in range-based for loops

* updated documentation for map_items API

* modified impl for serializing mappings

* fixed duplication error in CMake build target names

* added doxygen comments

* fixed ci errors

* added doxygen comments again

* Fix: made sure that empty documents just serialize to [] or {}

* fixed tabs

* fixed tabs again, missed a few ones

* added test cases for serializing root empty collections

* fixed path filtering in ubuntu.yml