Add a new plugin for comments framework
Add basic support for comments consisting of lines and formatted text
Drop redundant class for Markdown Lines
Add basic support for more comment items
Drop unnecessary CommentBrowser node
Browsers will be represented in Markdown as plain text and only have an
associated item but not a node. The previously introduced CommentBrowser
node is thus no longer needed.
Inline functions that are used only once
Allow shapes to have one of three predefined shape types
Avoid infinite recursion during style initialization
Add different diagram shape types (Rectangle, Ellipse, Diamond)
Add diagram connectors for all three basic shapes
Get rid of some code duplication
Fix browser items and add the corresponding Markdown parsing
Use normalized compass directions for shape connector points.
Add handler for comment diagrams to allow editing.
Introduce diagram shape styles (colors)
Handle impossible case more gracefully
Store CommentNode label as a list of lines
Add comment image items
Add comment image/browser scaling
Add unordered lists to comments