…t a time

this is the proper type to encapsulate a byte when data is available
or -1 when there is no data.

The reference to the upper USBDevice class is passed on
the EPHandler constructor.

Now the release() function only performs the action that is called for,
i.e. release the endpoint and let it receive data. All the buffers handling
has been inlined in the callers, this also slightly improves performance
because it allows to remove some redundant checks.

It makes no sense to have ::recv calling repeatedly ::read in this
case.

This change improves read performance when massive data is sent
via USB by exploiting the hardware capability to handle multi-packet
transfers autonomously.

This bypass the generic (but inefficient) implementation of Stream::readBytes
and uses an optimized version of readBytes than can do efficient multi-byte reads.

Timeout is checked on the next send attempt. Initial timeout is set to
70ms, after a time out occurs and the previous transfer is still not
complete a send will report as failed. If a send times out, a ZLP will
be in the send queue to check for future timeouts.

It’s no longer needed with the timeout mechanism in USBCore.

Removed DUE and added MKR1000

Port of arduino/Arduino#5362

This pachs allows C++ global constructors to run after hardware
initialization. This helps some libraries that setups hardware
in class constructor to work properly.

See also #169

This commit enables PWM on pin 11 instead of pin A4 on MKR1000 improving UNO pinout compatibility

Add support to link the ARM math (provided by CMSIS tools)

Add I2S support

Speeds up booting when sketch erases application flash on 1200bps touch
reset.

Fixes some compile errors and warnings

Use new CMSIS and CMSIS-Atmel packages

…tream_merge