Consolidation of derivation rules on Section B.3.1 (second part)

PDR3 and PDR4 could be combined in one as below:

• PDR3 from "If two relationships p(a,b):S and q(a,c):T exist, with S being Specialization and T being a structural, dependency, or dynamic relationship, then a relation r(b,c):T might be derivable." to "If two relationships p(a,b):S and q(a,c):T exist, with S being Specialization and T being a structural, dependency, or dynamic relationship, then a relation r(b,c):T, with the same direction as q, might be derivable."
• remove PDR4

Examples:

• from "Example 52: Potential Derivation from Another Relationship and a Specialization in Line" to "Example 52: Potential Derivation from Another Relationship and a Specialization in Opposite Derection"