CppAstNode astType usage should be something better

[bruntib]

The astType of a CppAstNode can be "usage". We use this for several reference types like function call, inheritance, etc. Instead of "usage" we should introduce "call", "inheritance", etc. Not to mention that we also have an astType for virtual function call, and the variable usages are also "read" or "write".

[bruntib]

There is also a TypeLocation which should be eliminated. We should use the manner of usage instead, like ParameterTypeLoc, GlobalTypeLoc, etc.

[bruntib]

A caught exception object is currently considered a local variable. A new type location type should be introduced on this:

try { ... }
catch (const MyType&) { ... }