method for IsReal was unnecessarily weak
declared IsDefinedOverSplittingField

+ used it in CentralIdempotentsOfInvolutiveAlgebra
  to mark real blocks: "c![999] := true" now means that
  CentralIdempotentsOfInvolutiveAlgebra = true and the block is real
+ now IsBlock and BlockOfIdempotent are able to set IsBlock = true
[RG] -> [Gow]
renamed BlockIdempotentInfo -> BlocksInfo
installed BlocksInfo for blocks (IsAlgebra and HasOne)
code simplification

relies on a dangerous but readable convention in GAP: list * list = number
fixed bug in CentralCharactersOfBlocks

where characteristic 2 was hard-coded
better documentation for CentralCharactersOfBlocks
better documentation for BlocksInfo
installed DefectClasses for blocks (IsAlgebra and HasOne)
better documentation for DefectClasses
renamed DecompositionMatricesOfBlocks -> DecompositionMatrixPerBlock
renamed BrauerCharacterDegreesOfBlocks -> BrauerCharactersDegrees
renamed CartanMatricesOfBlocks -> CartanMatrixPerBlock
renamed CharacterDegreesOfBlocks -> OrdinaryCharactersDegrees
removed obsolete declarations and installations of DefectClasses
renamed CentralCharactersOfBlocks -> CentralCharacters
relocated code
removed obsolete comments
renamed UnderlyingBrauerTable -> BrauerTable

+ installed it for IsAlgebra
+ used it to simplify the code for [ IsElementOfFreeMagmaRing ]