added P_Weak
Weaken causing issue...
proving Permutation
P_Perm proven
P_Weak admissible, now a lemma
building pieces derived from IPC proofs
P_contr Contradiction case proved
UnionElim case of disj_elimL_lhs proven
disj_elimL_lhs proven
disj_elimL_rhs proven
P_conj_elimL