Add overlay python object to act as inverse roi
Add overlay python object to act as inverse roi

Signed-off-by: Andrew Butt <f0e550b392ccab9f366ecc80ae525c032211a45e@seas.upenn.edu>

SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray