Improve padding, spacing and alignment of dialog layout.
Fix title capitalization.
Make file dialog wildcard string translatable.
Remove fixed initial dialog size to allow sizers to work their magic.
Replace OK button event handler with TransferDataFromWindow.
Remember last line width units between dialog instances and sessions.
Save configuration file settings in a separate group and remove GfxImport
prefix from the entry names.
Add fencing to dialog header file to prevent nested includes.
Fixes lp:1822568
https://bugs.launchpad.net/kicad/+bug/1822568
* Do not compile dxf old files.
* import gfx, gal mode: make absolute placement working.
* Import gfx in legacy canvas: use it and make interactive placement working
* Take imported line width in account. Ensure DXF line thickness is OK.
* handling empty files in legacy mode.