For those of us that don't like having to use a retro IDE only to program an ATtiny chip now and then.
Attached is a modified copy of https://github.com/TCWORLD/ATTinyCore
collection. The boards.txt file has been re-worked to comply with the 1.5.3 IDE hardware layout scheme.
ATtiny24, ATtiny25, ATtiny44, ATtiny45, ATtiny84, ATtiny85, ATtiny167, ATtiny861, ATtiny2316 & ATtiny4313
Unzip to your ArduinoDIR\hardware\arduino\ directory. Done.
1. Select an IC from the Tools>Board menu.
2. Choose the way it operates from the spiffy new Tools>Mode menu.
That's it, Happy Hacking.