GH-65 Fix "Paramters" typo

[stepio]

Issue #65

Fixed a typo in method's naming, also did a search and fixed the same in a couple of comments.
Warning: as existing API methods are renamed, it's a breaking change.

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[stepio]

Sorry, my bad, this almost duplicates #54, although I found and fixed one more occurrence in comments.

[mukhtar]

Thanks for the fix. (de)serialization doesn't seem to be impacted by the typos, however, it would be preferable to keep the existing methods with the typos for backwards compatibility, mark them as deprecated, and add two new methods with the fixes.

[stepio]

Thanks for feedback, you're right - it's safer to keep backward compatibility this way. Updated & force-pushed. Also slightly updated .gitignore file: added maven build folder and IntelliJ IDEA metadata files and folders.