Split "Protocol 1" opcodes out from "Protocol 0" opcodes

We already keep "Protocol 2" and "Protocol 4" opcodes separately, and
for a good reason - it must be clear for a person just by looking at
opcodes definition from which protocol version an opcode comes. However
at present Protocol 0 and Protocol 1 opcodes come all intermixed with
each other.

In the upcoming patches we'll be teaching Encoder to take desired pickle
protocol version into account (similarly to how pickle.dumps accepts desired
protocol version in Python), and then the encoder will have to use
different opcodes for different versions: for example if user asks to
produce "protocol 0" pickle stream it will be invalid to use "protocol
1" opcodes - e.g. BININT, EMPTY_TUPLE, etc.

So I went through

	https://github.com/python/cpython/blob/master/Lib/pickletools.py

for each opcode searching its protocol version and separated the opcodes
with proto=1 from protocol 0 opcodes.

ogorek.go

@@ -18,51 +18,56 @@ import (
 
 // Opcodes
 const (
+	// Protocol 0
+
 	opMark           byte = '(' // push special markobject on stack
 	opStop           byte = '.' // every pickle ends with STOP
 	opPop            byte = '0' // discard topmost stack item
-	opPopMark        byte = '1' // discard stack top through topmost markobject
 	opDup            byte = '2' // duplicate top stack item
 	opFloat          byte = 'F' // push float object; decimal string argument
 	opInt            byte = 'I' // push integer or bool; decimal string argument
-	opBinint         byte = 'J' // push four-byte signed int
-	opBinint1        byte = 'K' // push 1-byte unsigned int
 	opLong           byte = 'L' // push long; decimal string argument
-	opBinint2        byte = 'M' // push 2-byte unsigned int
 	opNone           byte = 'N' // push None
 	opPersid         byte = 'P' // push persistent object; id is taken from string arg
-	opBinpersid      byte = 'Q' //  "       "         "  ;  "  "   "     "  stack
 	opReduce         byte = 'R' // apply callable to argtuple, both on stack
 	opString         byte = 'S' // push string; NL-terminated string argument
-	opBinstring      byte = 'T' // push string; counted binary string argument
-	opShortBinstring byte = 'U' //  "     "   ;    "      "       "      " < 256 bytes
 	opUnicode        byte = 'V' // push Unicode string; raw-unicode-escaped"d argument
-	opBinunicode     byte = 'X' //   "     "       "  ; counted UTF-8 string argument
 	opAppend         byte = 'a' // append stack top to list below it
 	opBuild          byte = 'b' // call __setstate__ or __dict__.update()
 	opGlobal         byte = 'c' // push self.find_class(modname, name); 2 string args
 	opDict           byte = 'd' // build a dict from stack items
-	opEmptyDict      byte = '}' // push empty dict
-	opAppends        byte = 'e' // extend list on stack by topmost stack slice
 	opGet            byte = 'g' // push item from memo on stack; index is string arg
-	opBinget         byte = 'h' //   "    "    "    "   "   "  ;   "    " 1-byte arg
 	opInst           byte = 'i' // build & push class instance
-	opLongBinget     byte = 'j' // push item from memo on stack; index is 4-byte arg
 	opList           byte = 'l' // build list from topmost stack items
-	opEmptyList      byte = ']' // push empty list
-	opObj            byte = 'o' // build & push class instance
 	opPut            byte = 'p' // store stack top in memo; index is string arg
-	opBinput         byte = 'q' //   "     "    "   "   " ;   "    " 1-byte arg
-	opLongBinput     byte = 'r' //   "     "    "   "   " ;   "    " 4-byte arg
 	opSetitem        byte = 's' // add key+value pair to dict
 	opTuple          byte = 't' // build tuple from topmost stack items
-	opEmptyTuple     byte = ')' // push empty tuple
-	opSetitems       byte = 'u' // modify dict by adding topmost key+value pairs
-	opBinfloat       byte = 'G' // push float; arg is 8-byte float encoding
 
 	opTrue  = "I01\n" // not an opcode; see INT docs in pickletools.py
 	opFalse = "I00\n" // not an opcode; see INT docs in pickletools.py
 
+	// Protocol 1
+
+	opPopMark        byte = '1' // discard stack top through topmost markobject
+	opBinint         byte = 'J' // push four-byte signed int
+	opBinint1        byte = 'K' // push 1-byte unsigned int
+	opBinint2        byte = 'M' // push 2-byte unsigned int
+	opBinpersid      byte = 'Q' // push persistent object; id is taken from stack
+	opBinstring      byte = 'T' // push string; counted binary string argument
+	opShortBinstring byte = 'U' //  "     "   ;    "      "       "      " < 256 bytes
+	opBinunicode     byte = 'X' // push Unicode string; counted UTF-8 string argument
+	opAppends        byte = 'e' // extend list on stack by topmost stack slice
+	opBinget         byte = 'h' // push item from memo on stack; index is 1-byte arg
+	opLongBinget     byte = 'j' //  "    "    "    "    "   "  ;   "    " 4-byte arg
+	opEmptyList      byte = ']' // push empty list
+	opEmptyTuple     byte = ')' // push empty tuple
+	opEmptyDict      byte = '}' // push empty dict
+	opObj            byte = 'o' // build & push class instance
+	opBinput         byte = 'q' // store stack top in memo; index is 1-byte arg
+	opLongBinput     byte = 'r' //   "     "    "   "   " ;   "    " 4-byte arg
+	opSetitems       byte = 'u' // modify dict by adding topmost key+value pairs
+	opBinfloat       byte = 'G' // push float; arg is 8-byte float encoding
+
 	// Protocol 2
 
 	opProto    byte = '\x80' // identify pickle protocol