Added documentation for API
Refactored code and added method to the interface
Added method for retrieving type from a declaring type
Moved methods from SynthesisUnit to IModelInspector
Decided to move entities to model package due to their strong relation
Updated code to handle Float and Double types
Added string checker
Moved methods from IModelVisitor to IStringChecker
Added method in Entity and Type enums to refact more code
Added Char type to the Alloy model
Added support for Char type