Type aliases do not interact correctly with format specifiers

[bocchino]

If the type associated with a format specifier is an alias type, the implementation should use the underlying type for analysis and code generation. Currently it uses the alias type. This causes the following problems:

1. An alias of an integer type is not recognized as an integer type, so it can't be used with an integer format specifier such as x.
2. When generating code for a format corresponding to an alias type, the code generator writes %s, which is not correct in general.

• Fix analysis
• Add unit tests for fpp-check
• Fix code gen
• Add unit tests for fpp-to-cpp