Allow USB descriptor strings to be defined in boards.txt (redux)

[projectgus]

(This is a reworking of #1421 when I realised a much more elegant way to do it.)

As per discussion list:
https://groups.google.com/a/arduino.cc/forum/?hl=en-US&fromgroups#!topic/developers/Ml_djoFXyPU

I'll reply to that thread with more detail.

[cmaglie]

@projectgus

Thanks, I've merged almost all of your implementation, but I've changed your quotedSplit because it has some bugs that makes compiling fail on some boards. I made another version that allows two type of quoting with ' or with ", so you can write '-DUSB_PRODUCT="My product"'.

There is also a porting for the Due board, you can find it together with your commits starting from here and goind backward: d6a5e41

C

[projectgus]

Thanks so much Cristian! Commits look good.

I can't believe I forgot the Due, sorry about that. FWIW if I send you similar pull requests in future, feel free to bounce them back to me with issues to fix. Not my intention to pour more work on you, you seem plenty busy already. :)

• Angus

PS The unit tests for the string quoting tools are also a nice addition.