no more casts for bounded pointers
opt: removed size member from Read_Chunk_Ptr_Cont (list)
opt: removed size member from Mutation_Ptr_Cont (list)
opt: removed size member from Mutation_Cont (itree)
removed size member from Read_Entry_Cont (set)
opt: removed size member from Contig_Entry_Cont (list)
opt: removed size member from Read_Chunk_CE_Cont (itree)
opt: removed size member from Read_Chunk_RE_Cont (set)
opt: reduced Mutation size
opt: compressed Read_Chunk struct