Move SpecifyShape
Make a register for SpecifyShape.c_code
Make SpecifyShape work on the GPU and tests.
pep8
Move print op to the new gpu back-end.
remove useless comparison
Fix copy-pasted docstring.
fix doc.
update doc.
Merge pull request #1839 from nouiz/specify_shape

Specify shape and print op to the new gpu back-end