Starting the move to Qt5

Still not compiling, but actually reaching the compiling stage.
Minor issue: Path to Qt5 has to be manually inserted. This can probably set somehow differently in the Makefile or CMakeList from the path to qmake
Finished switch for cmake, actual compiling stage reached, but fails due to changes
between Qt4 and Qt5
Started changes Qt4->Qt5 upon every compilation error

qtpropertybrowser fully taken as is from qtsolutions, Qt5 version. So far, compiles.

Failure for the moment in library.cc:
reset() function called, strangely trace to QTextStream, then complains...
All code compiles under Qt5.

Now needs heavy testing.
Modified several things in order to compile without hunspell or libarchive
cf. issue #145 on patagui
Merge pull request #146 from LaTruelle/qt5

Qt5

Fix #145
Fix #141
update minimum cmake version to 2.8.11 for Qt5
remove unecessary qt svg module
qsettings category "general" -> "global"

fixes weird settings behavior
fix songbook option --data-dir -> --datadir
add missing var init
remove "default" book when building pdf
disable broken book page in preferences
fix path to extracted archive
Merge pull request #1 from patacrep/master

Pull from upstream