Init plugin system base code.
Update comments. Add Id.
Update comments in PluginSystem.
Add ActionSystem and its dependencies.
Add icon images. Update core plugin.
Add editor system.
Add HTML editor.
Add HtmlEdit plugin.
Add Formatting plugin. Rename HtmlEdit components.
Rename constants in Core.
Update HtmlEdit plugin.
Add Formatting plugin.
Add application revision.
Rename plugin member variables.
Add more formattings.
Modified plugin pro file.
Add editor actions.
Add source of HTML visual editor.
Add DocumentManager in Core. Modify mutex header when using singleton.
Add underlying document. Maybe should change to HTML source.