Add a notable effort to type check the quotation@@@.
Arrived to type check the `identifier_type' function but arrived
at a dead end in order to type check `NonPrimitive' computation values.
First attempt to resolve the mutual recursion between NonPrimitive
type constructor and Table.table type.
Add the implementation of the `lambda_type' handler.
Finish to implement the `cond_type' handler.
Rename the type variants for terms, adding the prefix `Tm...' to each one of them.