various updates to 0.1.7

[rurban]

• fix C++ g++-6/clang++-4 errors

• Fixed most compiler warnings -Wall -Wextra repro: CFLAGS="-Wall -Wextra -Wunused-parameter -Wc++-compat" ./configure && make

• add 2 new flags:

  • problem_nonstrict to yaml_parser_t
  • indentless_map to yaml_emitter_t

indentless_map is for backcompat with yaml readers.

It changes the default indent behavior of map elements,
advance the indent the children of the map
according to the spec: 6.1 Indentation Spaces:

      "Each node must be indented further than its parent node.  All sibling nodes
      must use the exact same indentation level.  However the content of each
      sibling node may be further indented independently."
      http://yaml.org/spec/1.2/spec.html#id2777534

This make it readable by YAML.pm (perl),
and behaves the same as all other YAML writers.

problem_nonstrict is to skip aborting on some reader errors:
"control characters are not allowed"
The error is set, but parsing is continued. This allows optionally
accepting invalid string values, copy-as-is, avoiding data-loss.

[sigmavirus24]

Hi @rurban! Thanks for collating all of this. It'd be easier to review, however, and would make our lives better if you could split this up into separate pull requests.

Fixing compiler errors and warnings is fine, but tossing in new code atop that makes things very difficult to review. Please split these out.

[rurban]

@sigmavirus24 no. I submitted these accumulated changes over the last year in various forms to the various proper upstream places. now this seems to be a new upstream. do it by yourself, or I'll have to fork it, when you are not able to maintain it and be able to discuss any problems. yaml is seriously broken and see no willingness to fix it upstream.

ingy promised to merge it for over a year now.

[perlpunk]

Just a note: @tlsa helped finding out that the yaml_free(version_directive) in commit "fix version_directive memory leak" is actually wrong. @tlsa's suggestion was:

if (version_directive_ref == NULL) {
        yaml_free(version_directive);
}

I confirmed that with:

% echo "%YAML 1.1\n--- foo" | ./tests/run-parser-test-suite
+STR
+DOC ---
=VAL :foo
-DOC
-STR

vs.

% echo "%YAML 1.1\n--- foo" | ./tests/run-parser-test-suite
+STR
+DOC ---
=VAL :\0\0\0
-DOC
-STR