Added wrapper over lookUpbindings, fixed merge conflicts, migrated code

[mannprerak2]

Closes dart-lang/native#532.

A wrapper is now generated for the bindings which need to look-up symbols from dynamic library.

• Replaced config init-function-name with wrapper-name.
• Handled name conflicts - Function-Function, Typedef - Function - Struct/Enum.
• Updated examples and clang_bindings, Updated tests.

[dcharkes]

I really like this.

We should use proper naming for the class we generate:

Clang clang; // Not called Bindings.
clang.clang_CXIndex_getGlobalOptions(...);

Or you want to go one step further, you could even think about using the prefix name replacer to remove the clang_ from the method names:

Clang clang;
clang.CXIndex_getGlobalOptions(...);

(Not for this PR, I just wanted to show that this feature is nice!)

[dcharkes]

data.bindings -> clang (import the name into here without a name).
clang -> clangTypes (change the import name).

That way both are related. Here, and everywhere else in the code.

It is kind of a pity that Dart does not have nested classes (dart-lang/language#336 and dart-lang/language#1049), as then we could have both as clang.functionCall and Clang.Type.

@eernstg Any other language features which might be handy in this situation?