Add support for Footnotes and endnotes

[PrzemyslawKlys]

This PR aims to resolve:

• https://github.com/EvotecIT/OfficeIMO/issues/152
• Adds ability to add end notes and foot notes

internal static void Example_DocumentWithFootNotesEmpty(string folderPath, bool openWord) {
    Console.WriteLine("[*] Creating standard document with footnotes/end notes");
    string filePath = System.IO.Path.Combine(folderPath, "Document with FootNotes02.docx");
    using (WordDocument document = WordDocument.Create(filePath)) {
        var paragraph = document.AddParagraph("Basic paragraph");
        paragraph.ParagraphAlignment = JustificationValues.Center;

        document.AddParagraph("This is my text").AddFootNote("This is a footnote to my text")
            .AddText(" continuing").AddFootNote("2nd footnote!");

        Console.WriteLine("EndNotes count " + document.EndNotes.Count);
        Console.WriteLine("EndNotes Section count " + document.Sections[0].EndNotes.Count);

        Console.WriteLine("FootNotes count " + document.FootNotes.Count);
        Console.WriteLine("FootNotes Section count " + document.Sections[0].FootNotes.Count);

        var lastFootNoteParagraph = document.AddParagraph("Another paragraph").AddFootNote("more footnotes!")
            .AddText(" more within paragraph").AddFootNote("4th footnote!");

        Console.WriteLine("Is paragraph foot note: " + lastFootNoteParagraph.IsFootNote);

        var footNoteParagraphs = lastFootNoteParagraph.FootNote.Paragraphs;

        Console.WriteLine("Paragraphs within footnote: " + footNoteParagraphs.Count);
        Console.WriteLine("What's the text: " + footNoteParagraphs[1].Text);
        footNoteParagraphs[1].Bold = true;

        document.AddParagraph("Testing endnote - 1").AddEndNote("Test end note 1");

        document.AddParagraph("Test 1");

        document.AddSection();

        document.AddParagraph("Testing endnote - 2").AddEndNote("Test end note 2");

        Console.WriteLine("EndNotes count " + document.EndNotes.Count);
        Console.WriteLine("EndNotes Section count " + document.Sections[0].EndNotes.Count);

        Console.WriteLine("FootNotes count " + document.FootNotes.Count);
        Console.WriteLine("FootNotes Section count " + document.Sections[0].FootNotes.Count);

        document.Save(openWord);
    }
}