+ Renamed Pval to Pvar
+ Substitution on types
- Removed restrictions on Expr export
+ Errors module
+ Counter for generating type vars
+ Type constraints
+ Unification
+ Typing environment
+ Typing of constants
+ Typing of primitives
+ Typing of patterns
+ Typing of expressions
+ Main type inference module
Merge branch 'feature/type-inference' into develop
+ gitignore update
+ Changelog update