Add support models with more than 256 type definitions

[111pontes]

YDK can't handle models with more than 256 type definitions. The limitation comes from libyang. We need to port the fix if available or implement it and contribute it upstream.

[einarnn]

Just FYI, this was a deliberate implementation decision by the libyang authors to conserve memory for their primary use cases. Any fix we contribute will need to ensure we do not substantially increase memory or CPU usage. We hit this issue during yangcatalog work as well, and for now this is not a priority for the libyang primary authors.

[ghost]

Fixed in latest code