Use native file dialog for save as image under linux
Add default file name parameter for getSaveAsImageName dialog
#9094: Del-key perfom 'delete selected features'
#9094: Other shortcut changes
#9094: Add Ctrl+D and D support for remove layers
#9094: fix invalid file
#9094: implements user/dev advices
#9094: fix invalid file
#9094: Auto-select adjacent last-removed node

Automatically selects the adjacent vertex to last removed selected node
#9094: '+' and '-' keys work as selector nodes

'+' and '-' select next and previous to current active node
respectively.
This commit is for demo proposes.
#9094: keyPressed can be overrided in MapTool

KeyPressed event of MapCanvas can be overrided in current MapTool. It
enables to use 'Delete/Backspace' key as default shortcut to delete
selected features, but it can be overrided in current maptool.
#9094: Show info messages about deleting features
#9094: AttributeTableDialog use del/backspace
 use
#9094: Use backspace in other similar code
Better conversion of QPainterPath to dxf
Improve dxf export for svg symbols
Remove legacy code
Remove drawEllipse from dxf paint engine (default implementation calls drawPolygon)
Export more simple markers to dxf
Fix circle position in dxf export