Update Project Tree (#847)

* Rename index textCounts to fileMeta and add main header level
* Add new icons for document layouts
* Add function in NWItem to describe the item
* Use the icons and description in the project tree and details panel
* Remove flags column and add status column with optional full text
* Update handling and display of header level in editor
* Fix potential bug in project tree
* Update tests

nw/assets/icons/typicons_colour_light/icons.conf

@@ -8,7 +8,7 @@
 
 [Main]
 name           = Typicons Colour Light
-description    = Coulorised icons for light GUI theme based on Typicons.
+description    = Colourised icons for light GUI theme based on Typicons.
 author         = Veronica Berglyd Olsen (adaptation)
 credit         = Stephen Hutchings (icon design)
 url            = https://github.com/stephenhutchings/typicons.font
@@ -28,6 +28,10 @@ cls_custom     = star.svg
 cls_archive    = delete.svg
 cls_trash      = trash.svg
 proj_document  = document-text.svg
+proj_title     = document-title.svg
+proj_chapter   = document-chapter.svg
+proj_scene     = document-scene.svg
+proj_note      = document-note.svg
 proj_folder    = folder.svg
 doc_h0         = heading0.svg
 doc_h1         = heading1.svg