Clean The Scrapyard

[zer0Kerbal]

@mblob suggests

Is your feature request related to a problem? Please describe.
for example, When using oh scrap, you may not want to keep 1st gens parts in the scrapyard.

Describe the solution you'd like
A small ui to select and trash parts in the scrapyard

Describe alternatives you've considered
When using "new part" action you can then discard parts, but on complex settings i have to individually select "new part" then discard. Really boring option. Anyway discarding part is a hassle.

#12