* minor changes in Op class and add ref impl for acosh
* acosh in new test framework
* add Acosh type test
* add SLT for Acosh
* run more test
* new acosh plugin test
* add visitor test
* fix test utils
* add template test for all supported types in Acosh
* add builder to template tests
* update grn template_plugin test
* update maste to feature branch
Patryk Elszkowski