Moderator: igrr
the "automatic prototyping" in 1.6.7 is ... different or broken or ... in short: doesn't work as before / expected.
I just hadn't time to check if only esp8266 sketches are incompatible or if it bites "original" AVR sketches, too?
One do not use a proxy when downloading anything with Arduino IDE.
and two if some how the files the board manager is downloads get corrupted. go find and delete them.