Upgrade from Qt4 to Qt5

[alastair]

With these changes I can compile gaia, but it's not yet tested.

There are many deprecation warnings that appear during compilation that should be fixed.

Some items are pending, such as a decision on cyclops (#91)

We have to decide how to test these changes:

• Fix unit tests with qt4, and ensure that they pass on qt5 too
• Build some svm models with both versions
• Set up a test freesound database and test that NN search results are the same on both

[antlarr]

Just in case it's useful, I've also made a patch to upgrade from Qt4 to Qt5 in order to build gaia packages for openSUSE Tumbleweed . You can see the patches I did at:
https://build.opensuse.org/package/show/home:alarrosa:branches:multimedia:libs/gaia2 . Specially the use-qt5.patch file.

I needed to work on that since openSUSE Tumbleweed doesn't have Qt4 nor python2 anymore, but I didn't submit them to this repository (nor to openSUSE) because I only did minimal testing so far and the use-qt5.patch also includes changes to use openSUSE standard directories (like installing libraries to /usr/lib64 instead of /usr/lib) that should be fixed in a more generic way before submitting here. In any case, at least high level audio analysis with essentia and the beta5 models seem to work fine.

In that project I linked above there's also a use-python3.patch file that might be interesting to complete #94 .

[alastair]

@antlarr thanks for this patch! I see that most of your changes are similar to the ones here.

I'm currently encountering a problem where with c++11, gvarlengtharray fails to compile because of the use of memcpy. Have you seen any error like that?
In any case, we're going to switch this back to use qvarlengtharray from qt, so it shouldn't be an issue in the long run.

[alastair]

I'm currently encountering a problem where with c++11, gvarlengtharray fails to compile because of the use of memcpy. Have you seen any error like that?

I managed to reproduce this as a warning, only when using g++ on debian, however I've fixed it in #107 by replacing gvarlengtharray with qvarlengtharray from qt. issue solved!