nifskope: 1.1.3 -> 2.0.dev7

`nifskope` v2 contains a lot of new features and a new, QT5-based UI
(see https://github.com/niftools/nifskope/releases). Additionally the
2.0 sourcetree exists for quite a while and after some short user tests
it seems fairly stable.

The following aspects have been changed:

* Use QT 5.9 rather than QT4 (see #33248).

* GCC7 support from upstream (gcc6 patch not needed anymore, build on
  GCC7 works fine), disabled `-Werror=format-security` can be used again
  as compiler flag.

* Patched broken paths in `NifSkope_targets.pri` to point to the proper
  dependencies (otherwise `<gli.hpp>` and `qhull` couldn't be found).

* Patched paths in `NifSkope.pro` to `lupdate` and `lrelease` (default
  `QT_*` paths point to `libsForQt5x.qtbase` which doesn't contain the
  needed binaries, instead they need to point to `libsForQt5x.qttools`).

* Added myself as maintainer.