moved to doxygen style

thanks Sebastin Gutsche and Max Horn for the wonderful work
clarified comments in code
fixed DefiningIdealOfLowerPartOfUnitaryGroup

it was computing DefiningIdealOfUnitaryGroup( F, r.2, r.3 ) instead of
DefiningIdealOfUnitaryGroup( F, r.2 )
IsLowerPartExtensionOfAffineSpaces now uses the whole remaining chain each step