Currently casting only works when a value is of an exact type.

Supporting type aliases is a commonly requested feature:

• Cannot cast alias variable to int32 #215
• doesn't handle named types #165
• Support cast defined type  #160
• feat: support type casting for interfaces created from basic types #235
• Support alias type's ToStringE #229
• Support string alias type's ToStringE and ToString functions  #209
• support int type alias #207
• modify function ToStringE to support type redefinition #109