Shared variant of Dynamic type; All read/write access operations in Dynamic backed by Read/Write lock guards; new shared() script function

Cargo.toml

@@ -34,6 +34,7 @@ no_index = []       # no arrays and indexing
 no_object = []      # no custom objects
 no_function = []    # no script-defined functions
 no_capture = []     # no automatic read/write binding of anonymous function's local variables to it's external context
+no_shared = []      # no explicit shared variables in the script code
 no_module = []      # no modules
 internals = []      # expose internal data structures
 unicode-xid-ident = ["unicode-xid"]  # allow Unicode Standard Annex #31 for identifiers.