* Fixes an implicit conversion.

* The actual value is only relevant when ioMode != PIO_NONE.

Fail early instead.

Fail early instead.

Fail early instead.

Fail early instead.

Fail early instead.

* Also fixes implicit type conversion of strlen return value.

* The filetype-specific DefRecord functions fail by calling Error if a
  record cannot be created.

* cdf_write_var_slice will never return an error code but call
  on internal error handling.

* cdfReadVarSliceDP always returned 0 because the callee terminates
  instead of returning an error code.

* Move functions related to streams to stream.c and
* move functions relating to library as a whole to cdi_int.c.
* Also eliminate STREAM_debug and replace with CDI_Debug.