declared and installed Coefficient
declared corresponding attributes for blocks

. DefectsOfBlocks
. CharacterDegreesOfBlocks
. BrauerCharacterDegreesOfBlocks
. CartanMatricesOfBlocks

installed their methods and used that to simplify the existing code
declared and installed CentralCharactersOfBlocks
coding style
store involutive algebra in CentralIdempotentsOfInvolutiveAlgebra

as the 1001-st entry of the PositionalObjectRep
declared and installed UnderlyingBrauerTable

for central idempotents of the group algebra
declared and installed Coefficients

for central group ring elements
fixed docu of IsRegular
declared and installed BlockIdempotentInfo
BlockIdempotentInfo is now a mutable attribute

use new DeclareAttributeWithDoc which allows "mutable" option
declared and installed UnderlyingGroupAlgebra

and simplified UnderlyingBrauerTable using it
CentralCharactersOfBlocks now stores the entries of its output list in corr. block record