Support media-attachments, folded sections, non-standard color highlight

[Argimko]

Hi @alxnbl, thank you for your great app! I would like to do some commits, the main is: 77ee584

Please, see PR commit descriptions for more details.

Thank you!

[alxnbl]

Thank you for these commits. At the first glance it looks great!

I will integrate it in the next release of the tool, after having done my regression tests.

[Argimko]

@alxnbl, please, when you have time, check the next complex commit.

1. Correctly process folded sections – closes OneNotes notes with folded/collapsed areas not converted #99
2. Correctly process non-standard text highlight color (Light Green, Teal, Gold, etc.)
3. (pending) Convert OneNote Text Tags to #hash-tags with Emoji icons
4. Added TemporaryNotebook class to store OneNote pages at temporary section for pre-processing such as: Sections unfold, Convert OneNote tags to hash-tags, Keep checkboxes, etc.
   • If pre-processing is needed for some page, it cloned to temp notebook with adjusted XML content and then exported to DocX. If page XML don’t changed due pre-processing, it exported to DocX from original place.
   • Move part of FillSectionPages() function and ProcessPageAttachments() from OneNoteExtensions.cs to ExportServiceBase.cs/ExportPage() because we need parsed XML page content for PageXmlPreProcessing()
5. Use installed Pandoc when it not found in exporter local folder
6. Refactoring based on Visual Studio suggestions:
   • Apply spell checker suggestions
   • Convert regular class constructors to primary
   • Made methods static where it applicable, across number of classes
7. Refactoring to simplify routing parameters between functions:
   • Use global static class OneNoteApp to communicate with OneNote Interop
   • Made class ConverterService static
   • Made class AppSettings fields static
8. Highlight warning message on Welcome app message about keeping a notebook backups

I am happy to work with your well-structured code! So I am trying to keep new code clear, and respect your code-style intent.

Thank you!

[alxnbl]

Wahou, great work thank you very much!
Very glad that you add extra features to the tool.
I am currently pretty buzy but I will try to find some time to review your code, launch regression tests and package a new version. Hopefully next month.