Various non-important fixes and comments

src/encode.c

@@ -307,7 +307,7 @@ byte_t* encode_seq_on_4_bits(const char* seq, int32_t length)
 			break;
 		default:
 			obi_set_errno(OBI_ENCODE_ERROR);
-			obidebug(1, "\nInvalid nucleotide base when encoding (not IUPAC)");
+			obidebug(1, "\nInvalid nucleotide base when encoding (not IUPAC), sequence: %s", seq);
 			return NULL;
 		}
 	}