Merge branch 'master' of github.com:arduino/Arduino
Add Print::write(const char *, size_t)

The new function just calls Print::write(const uint8_t *, size_t), but
this allows writing out a buffer of chars (without having to learn about
casts).
Add uint8_t* versions of methods in Stream

The new functions just call their char* equivalents, but this allows
reading bytes into a buffer of uint8_t as well as chars.
Remove unneeded casts in Print::write(const String&)

Now that Print::write(const char*) is also available, these casts are no
longer needed.
Implemented support for 1.5 libraries specification rev.2

- removed "arch" folder support
- allow to optinally use "src" folder
- slightly changed metadata

For more information see:
https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification
http://goo.gl/gfFJzU
Added a warning for library using the no longer supported "arch" folder
Use Files instead of String to handle paths in Compiler class.
IDE do not hide libraries with incompatible architectures
Added "category" field in libraries.
Added "license" field in libraries.
IDE warns if a library is compiled with an unsupported architecture
Added the possibility to override library compatibility check
Removed unused import
GSM library to format 1.5 rev.2
Audio library to format 1.5 rev.2
Use reinterpret_cast to cast __FlashStringHelper to const char*
sam: Optimized delayMicroseconds() (Rob Tillaart)

See #1121
Removed unused stuff from WiFi library.
Removed unused "socket.h" interface from WiFi library.

(that was probably an heritage from Ethernet lib)
Moved vanilla parts of WiFi library into common source folder.