Unify the error code

[nudles]

It would be better to have a error code list for debugging.
Then we can raise the errors.

Here are some example errors:

1. device not set or not match for input tensors to an operator
2. memory not allocated for a tensor
3. parameters not created in a layer
4. tensor shape not match
5. tensor dtype not match

[chrishkchris]

Yes, currently one of the problem in the debugging is that it do not tell which file and which line has problem.

I suggest we can add __FILE__, __LINE__ to incidate which file and which line when we handle the five examples errors in this issue. For examples:
https://github.com/apache/singa/blob/master/include/singa/io/communicator.h#L54

[XJDKC]

Yes, currently one of the problem in the debugging is that it do not tell which file and which line has problem.

I suggest we can add __FILE__, __LINE__ to incidate which file and which line when we handle the five examples errors in this issue. For examples:
https://github.com/apache/singa/blob/master/include/singa/io/communicator.h#L54

Yeah, we can use macros to achieve that. But @nudles suggested we can use an error code list. We can provide a table for users to look up the details of the error by using the error code they get.