Prefer static_cast to reinterpret_cast (#4223)

* Change reinterpret_cast -> static_cast wherever possible
* Remove more unnecessary `const_cast`s.

reinterpret_casts should be avoided for the same reason as c-style casts - they don't do any type-checking. reinterpret_cast was mainly being used for down-casting in inheritance hierarchies but static_cast works just as well while also making sure that there is actually an inheritance relationship there.

src/OSSupport/File.cpp

@@ -285,7 +285,7 @@ int cFile::ReadRestOfFile(AString & a_Contents)
 
 	// HACK: This depends on the internal knowledge that AString's data() function returns the internal buffer directly
 	a_Contents.assign(DataSize, '\0');
-	return Read(reinterpret_cast<void *>(const_cast<char *>(a_Contents.data())), DataSize);
+	return Read(static_cast<void *>(const_cast<char *>(a_Contents.data())), DataSize);
 }