valuearray.cpp Switch to using Q_ASSERT_X and Q_FOREACH

I learned Q_ASSERT_X is probably going to be more useful in
debugging the program.

And Q_FOREACH is more portable as it doesn't depend on c++ 11 features.
Rename my set function to replace as that's what QList calls it.
Implement the rest of ValueArray (especially the iterator)
valuearraytest add test coverage for many ValueArray functions.
Move registering ValueVTable_ValueArray to src/QGlib/init

QGlib/init was my best guess of where to put it, as its not
really part of QGst which is where most of the ValueVTable registrations
happen.