Fixes to make pbe faster (again after refactoring of xcpot) Changes for reanabling old CPP_66 functionality

-removing of variable icorr, use of member-functions instead
-removal of icorrkeys module
-removal of hybridmix module
-cleanup at several places

Bugfixes, put swapped some variables between hybrid/hybdat datatype, moved files from xc-pot to hybrid

Removed most of CPP_INVERSION

Introduced module types_rcmat with a general type for real/complex matrices
Introduced general IO for these matrices

eig-file/data IO is broken and hence the version is not useful yet.

Removed preprocessor switches CPP_SOC, CPP_INVERSION, CPP_APW, CPP_CORE.
Only a single fleur executable is built.

as this breaks shared memory parallelism

module variables as this will break shared memory parallelisation!

preprocessor statements to remove that code

Based on v0.26 hybrid branch