Add ignored_parts config option.

[cjwelborn]

The config key will contain part descriptions to ignore:

{
  "ignored_parts": [
    {"type": "Drawer Panel"},
    {"type": "Drawer Front", "width": 12.875}
  ]
}

...possibly with special keys to narrow the scope: width_max, length_min, or "width_range"=[11, 11.5].

Could even go so far as: "type_startswith": "Drawer"

Basic part-type ignoring was implemented in the B & M version, but this would be a more complete implementation.