* TDDFT RHS of CPHF equation using GAPW
Refectoring of ks_ref_potential and exstate_type
* TDDFT GAPW forces: RHS CPHF and direct forces
* Further GAPW/TDDFT Gradient terms
ADMM Slater X correction
* Update to new pointer scheme
* Remove duplicated code and debug statements
* Pretty
* update data
* Deallocate PW structure from qs_vxc in ks_reference
* Get rid of memory leaks
* rebase
* GAPW_XC bug fix for linear response
* GAPW/GAPW_XC linear response refactoring
* Prettify and update regtests
* Remove filter and adjust regtest value
* Pretty
* Linear response for ADMM/GAPW
* TDDFT/ADMM/GAPW excitation energies. More regtests. Some refactoring.
* Merge with upstream
* Optionally switch off ADMM XC correction in TDDFPT kernel
* GAPW_XC bug fix for linear response
* GAPW/GAPW_XC linear response refactoring
* Prettify and update regtests
* Remove filter and adjust regtest value
* Pretty
* Linear response for ADMM/GAPW
* TDDFT/ADMM/GAPW excitation energies. More regtests. Some refactoring.
* Merge with upstream
* Fix memory leak and non-assocoated pointer argument
Refactor matrix treatment in WFC and Linres code
Refactor some communication routines in WFC
Refactor spin treatment in WFC
Use Linres routines for MP2 gradients
Add XC and ADMM kernel to MP2 gradients
Remove unused variables and dead code
Add gradient and stress tensor for double-hybrid functionals
* Energy Correction moved to DFT section, new regtests
Towards Harris Functional Forces
Harris force: CPKS equations
Harris Forces Debug Code
Harris functional + external field and dipole
Harris forces: refactoring, CPKS solver
* Response: HFX and ADMM-HFX
Linear response: HFX and ADMM
* Debug Linres regtest adjustments
* Refactoring of hfx_derivatives: from mp2 specific to response
* Harris: HFX+ADMM ground state (1. part)
Harris forces for ADMM (not debugged)
* Harris functional using linear scaling methods
* Harris: solver and MAO