add MIT license file and license headers to the most important .F90 modules

source/KKRnano/source/AtomicCore_mod.F90

source/KKRnano/source/AtomicForce_mod.F90

source/KKRnano/source/BrillouinZone_mod.F90

source/KKRnano/source/CalculationData_mod.F90

source/KKRnano/source/ConfigReaderDictionary_mod.F90

source/KKRnano/source/ConfigReader_mod.F90

source/KKRnano/source/Constants_mod.F90

source/KKRnano/source/EBalanceHandler_mod.F90

source/KKRnano/source/EnergyMeshHelpers_mod.F90

source/KKRnano/source/EnergyMesh_mod.F90

source/KKRnano/source/Errors_mod.F90

source/KKRnano/source/Exceptions_mod.F90

source/KKRnano/source/GauntCoefficients_mod.F90

source/KKRnano/source/GaussWeights_mod.F90

source/KKRnano/source/Harmonics_mod.F90

source/KKRnano/source/JelliumPotentials_mod.F90

source/KKRnano/source/KKRnano.F90

source/KKRnano/source/KKRzero_mod.F90

source/KKRnano/source/LICENSE

source/KKRnano/source/LatticeVectors_mod.F90