Add "interface" as reserved keyword and synonym for "class"

SquiLu/squirrel/sqcompiler.cpp

@@ -894,6 +894,7 @@ start_again:
             break;
         case TK_CLASS:
         case TK_STRUCT:
+        case TK_INTERFACE:
             ClassStatement();
             break;
         case TK_ENUM:

SquiLu/squirrel/sqcompiler.h

@@ -58,6 +58,7 @@ struct SQVM;
     ENUM_TK(INLINE)\
     ENUM_TK(INSTANCEOF)\
     ENUM_TK(INTEGER)\
+    ENUM_TK(INTERFACE)\
     ENUM_TK(UNSIGNED_INTEGER)\
     ENUM_TK(UNSIGNED_LONG_INTEGER)\
     ENUM_TK(LONG_INTEGER)\

SquiLu/squirrel/sqlexer.cpp

@@ -102,6 +102,7 @@ SQTable * SQLexer::GetKeywords()
 	ADD_KEYWORD(int8_t, TK_LOCAL_INT8_T);
 	ADD_KEYWORD(in, TK_IN);
 	ADD_KEYWORD(inline, TK_INLINE);
+	ADD_KEYWORD(interface, TK_INTERFACE);
 	ADD_KEYWORD(int_t, TK_LOCAL_INT_T);
 	ADD_KEYWORD(let, TK_LOCAL);
 	ADD_KEYWORD(__LINE__,TK___LINE__);