Update PinChangeInterrupt.cpp

base is given by parameters from the macro later
Merge pull request #252 from thomasahlendorf/patch-2

Update PinChangeInterrupt.cpp
Add empty() to IOStream::Device and drivers
Allow thread yield during analog conversion wait.
Protect toggle and pulse.
Add weekday symbols and clean up epoch definitions.
Update benchmark run. Clean up CosaBenchmarkPins.
Benchmark run after latest updates.
Benchmark run after latest updates.
Check that empty() works
Make IOBuffer::empty virtual
Fix CosaIOBuffer testing of gets()

As recommended by Mikael.
Merge pull request #255 from jediunix/IOStream-empty

Add empty() to IOStream::Device and drivers
Fix CDC::begin hang when no host is present

When no host is present CDC::begin hangs in USBDevice::attach.  This
change waits 2 seconds before giving up on the host.  If no host is
connected within that time USB data is disabled but USB power regulator
is left on in case power comes from a USB power adapter.
Merge pull request #256 from jediunix/CDC-begin-hang-fix

Fix CDC::begin hang when no host is present
Adding support for using Cosa directly with GCC-AVR.
Cleanup build script and install description.
Cleanup.
Fix CDC auto-reset for Mac OSX

The OSX USB driver apparently behaves differently than other platforms
with regard to baud rate and DTR handling.  This fix forces DTR low for
1 second in ard-reset-arduino to guarantee that Cosa will reset
regardless of host platform behavior.  Also corrected a comment about
the watchdog time to match the wdt_enable.
Fixed menu string handling; missing ripple effect of str_P.