Fix #300: Make literals have the same constants as their types.
Add checkPostCondition to Literalize
Check not only value equality of constants in Literalize postcondition but also type eqality
Fix Literalize: (Long(2):Any) == (Int(2): Any) but constants aren't.
Merge pull request #301 from dotty-staging/fix/#300-literals

Fix #300: Make literals have the same constants as their types.