In progress: [Issue 27] Negative numbers not supported for default values
https://code.google.com/p/protobuf-dt/issues/detail?id=27

In progress: [Issue 28] Add support for deprecated message fields
https://code.google.com/p/protobuf-dt/issues/detail?id=28

Added initial work in the grammar.

com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext

diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
index fd6b46b..5b36a68 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
@@ -58,7 +58,7 @@
 
 Property:
   modifier=Modifier type=AbstractTypeReference name=ID '=' index=INT (('[' 'default' '=' default=ValueRef
-  ']') | ('[' 'packed' '=' packed=BooleanRef ']'))? ';';
+  ']') | ('[' 'packed' '=' packed=BooleanRef ']') | ('[' 'deprecated' '=' deprecated=BooleanRef ']') )? ';';
 
 enum Modifier:
   required
@@ -142,6 +142,6 @@
 MessageReference:
   type=[Message | QualifiedName];
 
-terminal INT returns ecore::EInt: ('0'..'9')+;  
-terminal FLOAT returns ecore::EFloat: ('0'..'9')* ('.' ('0'..'9')+)?;
+terminal INT returns ecore::EInt: ('-')? ('0'..'9')+;  
+terminal FLOAT returns ecore::EFloat: ('-')? ('0'..'9')* ('.' ('0'..'9')+)?;
   
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