Add syntax specification to .proto files (issue #167)

Eliminates a warning on protoc 3.0.

examples/cmake_simple/simple.proto

 // A very simple protocol definition, consisting of only
 // one message.
 
+syntax = "proto2";
+
 message SimpleMessage {
     required int32 lucky_number = 1;
 }

examples/network_server/fileproto.proto

@@ -2,6 +2,8 @@
 //
 // See also the nanopb-specific options in fileproto.options.
 
+syntax = "proto2";
+
 message ListFilesRequest {
     optional string path = 1 [default = "/"];
 }

examples/simple/simple.proto

 // A very simple protocol definition, consisting of only
 // one message.
 
+syntax = "proto2";
+
 message SimpleMessage {
     required int32 lucky_number = 1;
 }

examples/using_double_on_avr/doubleproto.proto

 // A message containing doubles, as used by other applications.
+syntax = "proto2";
+
 message DoubleMessage {
     required double field1 = 1;
     required double field2 = 2;

examples/using_union_messages/unionproto.proto

@@ -5,6 +5,8 @@
 // but they are commonly implemented by filling out exactly one of
 // several optional fields.
 
+syntax = "proto2";
+
 message MsgType1
 {
     required int32 value = 1;

tests/alltypes/alltypes.proto

+syntax = "proto2";
+// package name placeholder
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];

tests/backwards_compatibility/alltypes_legacy.proto

+syntax = "proto2";
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];

tests/callbacks/callbacks.proto

+syntax = "proto2";
+
 message SubMessage {
     optional string stringvalue = 1;
     repeated int32 int32value = 2;

tests/common/person.proto

+syntax = "proto2";
+
 import "nanopb.proto";
 
 message Person {

tests/common/unittestproto.proto

+syntax = "proto2";
+
 import 'nanopb.proto';
 
 message IntegerArray {

tests/cyclic_messages/cyclic.proto

@@ -2,6 +2,8 @@
 // These can only be handled in pointer/callback mode,
 // see associated .options files.
 
+syntax = "proto2";
+
 message TreeNode
 {
     optional int32 leaf = 1;

tests/enum_sizes/enumsizes.proto

@@ -4,6 +4,8 @@
  * a bit of a problem for the encoder/decoder (issue #164).
  */
 
+syntax = "proto2";
+
 import 'nanopb.proto';
 
 option (nanopb_fileopt).long_names = false;

tests/extensions/extensions.proto

+syntax = "proto2";
+
 import 'alltypes.proto';
 
 extend AllTypes {

tests/field_size_16/alltypes.proto

+syntax = "proto2";
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];

tests/field_size_32/alltypes.proto

+syntax = "proto2";
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];

tests/fuzztest/SConscript

@@ -2,16 +2,19 @@
 
 Import("env", "malloc_env")
 
+def set_pkgname(src, dst, pkgname):
+    data = open(str(src)).read()
+    placeholder = '// package name placeholder'
+    assert placeholder in data
+    data = data.replace(placeholder, 'package %s;' % pkgname)
+    open(str(dst), 'w').write(data)
+
 # We want both pointer and static versions of the AllTypes message
 # Prefix them with package name.
 env.Command("alltypes_static.proto", "#alltypes/alltypes.proto",
-            lambda target, source, env:
-                open(str(target[0]), 'w').write("package alltypes_static;\n"
-                                                + open(str(source[0])).read()))
+            lambda target, source, env: set_pkgname(source[0], target[0], 'alltypes_static'))
 env.Command("alltypes_pointer.proto", "#alltypes/alltypes.proto",
-            lambda target, source, env:
-                open(str(target[0]), 'w').write("package alltypes_pointer;\n"
-                                                + open(str(source[0])).read()))
+            lambda target, source, env: set_pkgname(source[0], target[0], 'alltypes_pointer'))
 
 p1 = env.NanopbProto(["alltypes_pointer", "alltypes_pointer.options"])
 p2 = env.NanopbProto(["alltypes_static", "alltypes_static.options"])

tests/intsizes/intsizes.proto

@@ -6,6 +6,8 @@
  * otherwise. E.g. uint32 + IS_8 => uint8_t
  */
 
+syntax = "proto2";
+
 import 'nanopb.proto';
 
 message IntSizes {

tests/message_sizes/messages1.proto

+syntax = "proto2";
+
 enum MessageStatus {
     FAIL = 0;
     OK = 1;

tests/message_sizes/messages2.proto

+syntax = "proto2";
+
 import 'nanopb.proto';
 import 'messages1.proto';
 

tests/missing_fields/missing_fields.proto

 /* Test for one missing field among many */
 
+syntax = "proto2";
+
 message AllFields
 {
     required int32 field1 = 1;