Added posibility for developer to deploy aditional Qt plugins through a
list of plugins directories and plugins, relative path to the Qt plugins
directory
if xcbglintegrations plugin not deployed then we get
following error message when try to run AppImage application:
"QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor
EGL are enabled"
we should include xcbglintegrations plugin when libxcb-glx.so found in
library list (obtained from ldd output). Some applications do not
depends on libQt5OpenGL.so but depends on libxcb-glx.so.
and issue a proper error message if not.
When using linuxdeployqt for example in OBS and packages can not
be installed, it can happen that the desktop file is not existing.
This error message makes debugging easier.
Without verbose logging (which is really spammy) this information is
otherwise not available, but it can be very helpful in finding out
what's causing the problem.
Refactor the project structure to make it build as a "Qt module". It's a first step to get this tool closer to Qt.
The main advantage here is: Simply running:
```
qmake
make
make install
```
will compile and install the tool into your Qt installation, and make it a part of your Qt just like any other tool (qmake, etc.)