Fix reshape on scalars/empty arrays (#158)

* test reshape corner cases

* pt.reshape: codegen handle reshapes on scalars and empty reshapes

Co-authored-by: Alex Fikl <alexfikl@gmail.com>

* Wrong argument count to reshape is a TypeError

* Missing article in error message

Co-authored-by: Alex Fikl <alexfikl@gmail.com>
Co-authored-by: Andreas Klöckner <inform@tiker.net>