- Run spec-cleaner
- Simplify conditions
- Use cmake macros
- Drop unused dependencies
- Drop obsolete macros
- Adjust changelog to follow patch guidelines
- Fix changelog formatting

- further cleanups and corrections in specfile:
* BuildRequire just git-core, not git
* rewrite BuildRequires: to use pkgconfig() for all the devel packages that support it
* reenable use of %{_smp_mflags} in make call
* remove unneeded static library libqx11embedcontainer.a from package
* comment out BuildRequires: to some 32bit devel packages for now (from an upstream list of build requirements)
- Drop not needed patches:
* lmms-fix.patch
* lmms-code-min.patch
* lmms-code-macro.patch
* lmms-carla.patch
* lmms-code-indent.patch
* lmms-1.1.3-fix-wrong-comparison-logic.patch
* lmms-1.2.0-undefined_ref.patch
* lmms-no-Werror.patch

- update to 1.2.0rc6 using obs_scm source service, reworked patches and spec
* rc6 release tarball misses some external submodule sources and doesn't compile, so use obs_scm
* workaround the illegal "-" char in official version string (1.2.0-rc6)
* modify/add BuildRequires to work for a Qt5 build
* update and rename lmms-1.0.0-crippled_stk.patch to lmms-1.2.0-crippled_stk.patch
* remove obsolete patches (applied upstream, problem fixed otherwise or pointing at now non-existing code)