Arduino team is proud to release a new Arduino IDE 1.6.6 and updated cores for AVR 1.6.9, SAM 1.6.5, SAMD 1.6.2. 723 issues were closed and 147 pull requests merged. Well done!

Via Arduino.cc:

Most intriguing features are:

  • Long-awaited new arduino-builder: this is a pure command-line tool which takes care of mangling the code, resolving library dependencies and setting up the compilation units. It can also be used as a standalone program in a continuous-integration environment
  • Pluggable USB core: your Arduino can finally act as a lot of different USB devices without any need to change the core, thanks to the new modular architecture. Libraries based on the new subsystem are already being developed!
  • Serial plotter: you can now plot your data in realtime, as easy as writingSerial.println(analogRead(A0)) inside your loop
  • New goodies for library developers, like unlocked examples while developing and optional linkage into an archive
  • ArduinoISP example has been improved a lot and now you can flash your AVR chip using ANY other board (including third-party ones :) )
  • Both Libraries and Boards managers notify if a library/core can be updated with a simple popup – no more outdated code floating around!
  • A LOT of bug fixes, adjustments, documentation refinement thanks to our tireless users and contributors. The complete list of fixes and credits is available here.