Coverity Scan fixes #1

[djb-rwth]

This PR includes:

• 40+ Coverity Scan high priority fixes; the fixes have been confirmed by Coverity Scan
• Transferring all remaining doxygen comments from .c files to .h files

Due to the number of fixes, it requires detailed PubChem testing.
More medium priority fixes to follow, but posting these now in a timely manner as agreed.

[JanCBrammer]

Note to myself and other reviewers: since the PR contains mostly style changes, a lot of effort goes into visually searching the diffs for semantic changes (i.e., the fixes). To view only the semantic changes check the "Hide whitespace" box in the review configuration (https://github.blog/changelog/2021-10-14-hiding-whitespace-is-now-remembered-for-each-pull-request/).

@djb-rwth, some files contain only style changes (e.g., mol2atom.c). Could you remove those from the PR? I feel like it's better to limit the style changes to files that are touched anyway for fixing. Otherwise the PRs / diffs get impractical to review.

[djb-rwth]

@djb-rwth, some files contain only style changes (e.g., mol2atom.c). Could you remove those from the PR? I feel like it's better to limit the style changes to files that are touched anyway for fixing. Otherwise the PRs / diffs get impractical to review.

Done.

[djb-rwth]

Hi @JanCBrammer,
Works now at my end, but the tests are a dud -- please look into this.

[JanCBrammer]

@djb-rwth, we were asserting that MakeINCHIFromMolfileText dies. Now that you've fixed MakeINCHIFromMolfileText, the test fails because it no longer dies. I've changed the assertion to check for successful InChI computation (see my latest commit), which makes the test pass.

[JanCBrammer]

@djb-rwth, could you merge this PR?

[djb-rwth]

@djb-rwth, we were asserting that MakeINCHIFromMolfileText dies. Now that you've fixed MakeINCHIFromMolfileText, the test fails because it no longer dies. I've changed the assertion to check for successful InChI computation (see my latest commit), which makes the test pass.

Hi @JanCBrammer,
Thanks for your quick action regarding this.