Add nm_bool to dia_init and add sptype switch to sparse_to_nmatrix and typo fix

[Uditgulati]

No description provided.

[Uditgulati]

@prasunanand I've changed some elements arrays' data types to void*, so that any type can be assigned to it. This will prevent the nesting of dtpe and sptype switch statements.

Also, I think we can take out some common code in nm_sparse_to_nmatrix and nm_sparse_to_array to a separate function. This will reduce code repetition. What do you think?

[Uditgulati]

@prasunanand void* as function parameter did not work. I found 2 possible solutions to this. One is using an enum structure for types. Second is to make the function as a macro and pass the type.

[prasunanand]

Please write code and explain in this thread.

[prasunanand]

keep it on hold, currently.

[Uditgulati]

Part of #21. Closing this one.