Itf inheritance cast

Feature/bugfix
===========

Bindings using type-hierarchy-related interfaces now have C cast generated where needed.

Pre-requisite
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Accepting Pull Requests https://github.com/MIND-Tools/mind-compiler/pull/8 and then https://github.com/MIND-Tools/mind-compiler/pull/11 (https://github.com/MIND-Tools/mind-compiler/pull/11 is already dependending on https://github.com/MIND-Tools/mind-compiler/pull/8) ; contribution should then be reduced to commit b3dde39fde713d4c63fd778c4c30ee7e822a70db

Issue description
-----------------------

C compilers raise a warning on pointer casts when trying to initialize a binding from an I1 interface type struct pointer with an I2 destination interface struct, where I2 extends I1.

Solution
-----------

Detection on binding check and tag the according AST interface/binding nodes to add the necessary cast with StringTemplates.