fixed LinearRegularity

and added it to intrinsic_attributes_specific_shared_with_subobjects_and_ideals
coding style
added FIXME comment
deleted obsolete comment
split method for CastelnuovoMumfordRegularity
added FIXME comment
use minus_infinity := HOMALG_TOOLS.minus_infinity

(needs ToolsForHomalg v2014.12.08)
declared and installed LinearRegularityInterval

and rebased LinearRegularity on it