- updated Drilling Tool to use the new settings
- updated the Excellon Editor: the default_data dict is populated now on Editor entry
- Excellon Editor: added a new functionality: conversion of slots to drills
- Excellon UI: added a new feature that is grouped in Advanced Settings: a toggle tools table visibility checkbox
- fixed partially the Excellon Editor to work with the new data structure
- fixed Excellon export to work with the new data structure
- fixed all transformations in the Excellon object attributes; still need to fix the App Tools that creates or use Exellon objects