declared and installed DefiningIdealOfMiddlePartOfUnitaryGroupUsingAdaptedBasis

and reset DefiningIdealOfMiddlePartOfUnitaryGroup to the old behavior
DefiningIdealOfUnitaryGroup for IsHomalgFiltration is now an attribute

it was mistakenly named DefiningIdealOfUnitary from previously
DefiningIdealOfUnitaryGroupModuloIdeal, I deleted too much :)

+ relocated method to attributes section
relocated methods for DefiningIdealOfUnitaryGroup for IsHomalgModule

to attributes section
renamed ideal I to J in doku
declared, installed, and documented DefiningMorphismOfUnitaryGroup

for IsHomalgFiltration

+ simplified DefiningIdealOfUnitaryGroup for IsHomalgFiltration
  using the new DefiningMorphismOfUnitaryGroup
InducedFiltration now allows empty indets
declared, installed, and documented DefiningMorphismOf*PartOfUnitaryGroup

DefiningMorphismOf*PartOfUnitaryGroup =
. DefiningIdealOfUpperPartOfUnitaryGroup
. DefiningIdealOfMiddlePartOfUnitaryGroup
DefiningIdealOf*PartOfUnitaryGroup now calls DefiningMorphismOf*PartOfUnitaryGroup