Updated delete icon to Material Design

Copied from the official Google Material Design icon repo
Merge pull request #11 from JordiOrlando/master

Update delete icon to Material Design

Google has always been suspicious of the old trashcan artwork.  It came from MIT's Open Blocks, which despite claiming to be open source is known to have some copyrighted resources (click sound is stolen from MS Windows 95).  A thorough search could not locate any known origin for the trashcan, so we used it, warily.