Rescale the waterfall pixmap when the GUI is resized

Previously the waterfall would be blacked out when the GUI was resized.
Add Qt 5 support.
Only include Qt widgets if we are using Qt 5.
Merge pull request #76 from weinholt/master

Rescale the waterfall when resizing
Updated.
Updated readme.
Fix mouse input with latest Qt 4.8
Add HackRF Jawbreaker to æist of supported devices.
Merge csete master branch 'upstream/master'.
Add HackRF sample rates.
port to gnuradio 3.7 API
Add usable version string for release builds.
Recommend gnuradio 3.6.5.1 when using gr-audio.
Make output device selector editable with when using gr-audio.

Related to issue #50.
Always reset audio output device on Mac OS X.

This hopefully fixes issue #66 and issue #78.
Add define for identifying OSX in non-Qt code.
Updated news file.
Ensure that FFT window is reset when FFT size changes.

Closes issue #70.
Updated readme.
Merge pull request #80 from pinkavaj/gnuradio_3.7_02

Switch to gnuradio 3.7 API (use gr3.6 branch for legacy).