If the SubExpr is changed then the ImplicitCast is invalid.
Implement visitor deriving callee functions in advance.
Merge branch 'master' of https://github.com/vgvassilev/clad
Add initial implementation of tests.
Testing the derivation of struct functions and class methods.
Merge pull request #6 from mvassilev/master

Implement visitor deriving callee functions in advance. If the SubExpr is changed then the ImplicitCast is invalid. Create more tests.