Added a GUI

Using Qt5 for the GUI.

Added a Qt project file tabloid.pro
To compile on Linux:
qmake
make
You need Qt5 and aubio installed.

The earlier Tabloid files were moved under src/core while src/gui will be where the gui files are located.
The main file, tabloid.cpp will be in src

TabloidWindow is the current main window for Tabloid. It just has an open button and a transcribe button for now.