The current fkYAML doesn't allow the document end marker (...) omitted before a new YAML document like the following YAML snippet (extracted from the yaml-test-suite's 35KP/in.yaml):

--- !!map
? a
: b
--- !!seq
- !!str c
--- !!str
d
e
# Note that the last multiline plain scalar isn't supported by fkYAML yet.

Parsing the above YAML with fkYAML causes a false parse error which says "invalid end-of-directives marker (---) found in the contents.".
To resolve the false error, this PR has changed the implementation to allow the document end marker omitted, and the library thus assumes no directives preceeded in the next YAML document instead.

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• Changes are described in the pull request or in a referenced issue.
• The test suite compiles and runs without any error.
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Please don't

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