PICT: simplify skipping of reserved opcodes

[Kristine1975]

There are various if (opcode <= 0x...) checks to skip unknown/reserved opcodes:

resource_dasm/src/QuickDrawEngine.cc

Lines 1268 to 1294 in a4cab63

	} else if (opcode <= 0x01FF) { // args: 2
	this->pict_skip_2(r, opcode);
	} else if (opcode <= 0x02FE) { // args: 4
	r.go(r.where() + 4);
	} else if (opcode == 0x02FF) { // args: 2
	// nop (essentially) because we look ahead in the 0011 implementation
	} else if (opcode <= 0x0BFF) { // args: 22
	r.go(r.where() + 22);
	} else if (opcode == 0x0C00) { // args: header
	// Currently we don't do anything with the data in this subheader, so just
	// check that its version makes sense and then ignore it
	PictSubheader h = r.get<PictSubheader>();
	if ((h.v2.version != -1) && (h.v2e.version != -2)) {
	throw runtime_error(string_printf("subheader has incorrect version (%08X or %04hX)",
	h.v2.version.load(), h.v2e.version.load()));
	}
	} else if (opcode <= 0x7EFF) { // args: 24
	r.go(r.where() + 24);
	} else if (opcode <= 0x7FFF) { // args: 254
	r.go(r.where() + 254);

According to IM Imaging with Quickdraw - Appendix A this code could be simplified:

Note: For opcodes $0100-$7FFF, the amount of data for opcode $nnXX = 2 times nn bytes.