When refactoring recently the PHONE_MIGRATE_X error
wrt exception handling [1] I removed the dubious/obsolete
"settings" part, but I mistakenly removed the URL which
tells library consumers that if they face this exception,
it's actually a bug of the library that they should report.
[1] 77867b44e6
There are different kind of MIGRATE errors that could be
thrown by the Telegram API, as evidenced by this recent
change:
b06f8a8e11
So this rename tries to make it consistent to the new
exception names:
* FILE_MIGRATE_x -> FileMigrationException
* USER_MIGRATE_y -> UserMigrationException
* PHONE_MIGRATE_z -> PhoneMigrationException
Instead of throwing a System.FormatException, capture the URL
thrown by the library itself so that the developer configures
the API_ID and API_HASH and places them in the app.config file.
For these tests to pass you not only needed to change
the app.config file but the .cs file as well with your
API settings (Hash & ID).
So let's put everything of them in the app.config so
it's easier to discover.
Parsing the message of an exception to decide what to do
next is a bad practice, because it's easy that the message
might be changed by mistake in the future. To enforce the
coupling in a stronger way it's better to use exceptions
of different type depending on the kind of error, so that
we rely on the compiler enforcing the behaviour when doing
changes in this error handling areas in the future.
This also makes the code a bit more simple and readable.
This change is good because:
a) It's better to target a lower target framework version if
the project doesn't necessarily depend on the new features
of the newer versions (so, bigger target audience).
b) It lets compile the project with implementations of the
.NET Framework that are not compatible with 4.5.2. For example,
after this change I can successfully build TLSharp with the
Mono v4.2.1 that comes in my Ubuntu Linux 16.04.1.
