[FEATURE]: Start implementation of native dxf export
Write dxf header and eof
First implementation of dxf feature writing (but it does not work yet)
Write additional header field and table section
Dxf: add more header fields, min/max extent and a test linestyle
More symbology updates for dxf
Prepare color palette matching for dxf
Fix TABLE sections
Dxf color palette
Try to find closest color in dxf palette
Support multilines / polygons / multipolygons (as closed linestrings for now)
Add dxf export gui and menu entry in qgisapp
Implement line width and symbol level support
Use linetype 1 for polygons, check if iodevice is already open
Write linetypes for simple line with custom dash pattern
Fix bug in linestyle export
Move dxf dash writing into separated function
First attempt to write AC1018
Use AC1009 only
Write blocks for point symbols