Change RELEASE number in initsysvar.cpp

Was set tp 8.5.1 but we lack a number of features that IDL>8 has and are checked by IDLAstro procedures. Noticeably graphic functions and some oo properties.
Better to play safe with a version 7
One can always change the alleged version using the --fakerelease command line switch

src/initsysvar.cpp

@@ -1018,7 +1018,7 @@ namespace SysVar
     ver->NewTag("OS_NAME", new DStringGDL(SysName));
 #endif
 
-    ver->NewTag("RELEASE", new DStringGDL( "8.5.1")); //changed since /NAN is no mere needed.
+    ver->NewTag("RELEASE", new DStringGDL( "7.0")); //Reasonable value as we do not have the new graphic functions.
     ver->NewTag("BUILD_DATE", new DStringGDL(BUILD_DATE));
     ver->NewTag("MEMORY_BITS", new DIntGDL( sizeof(BaseGDL*)*8));
     ver->NewTag("FILE_OFFSET_BITS", new DIntGDL( sizeof(SizeT)*8));