Changed: Updated Readme to reflect release 0.8.1

Changed: CommonMark converter to Markdig

Changed: Updated PDFSharp and HTMLRenderer.PDFSharp accordingly
Changed: Updated NPP.net Plugin Template

Added: Ability to load local image files

Added: Options to open an exported PDF or HTML

Changed: Updated appveyor.yml with build tag

Changed: Updated readme

Added: Description

Fixed: Bug evaluated file extensions with leading dot leading to issues

Added: Version 0.5.0 options dialog description

Merge pull request nea#12 from dail8859/other-view

Fixed: Handle rendering markdown in either Editor views