Rewrite of the code generation script. (#26)

* Generate CTensorFlow api calls directly.

* Regenerated bindings.

* Minor update.

* Switched to eager-mode generated ops.

* Added support for output lists.

* Minor tweak.

* Minor tweak.

* Bug fix.

* More bug fixes.

* More bug fixes.

* Minor tweaks.

* Made a couple more bug fixes.

* Fixed a bug related to type arguments.

* Added support for function-valued attributes.

* Added support for string-valued tensors.

* Bug fix for the string-valued versions of the ops.

* Minor bug fix related to string data types.

* Fixed a bug related to the inferred tensor array counts.

* Minor improvements to the format of the generated code.

* Switched to using a 'TFE_Op' struct.

* Added '@usableFromInline' to 'TFE_Op'.

* Removed argument labels from all functions in 'TFE_Op'.

* Bug fixes to the 'TFE_Op' implementation.

* Minor bug fix.

* Made generic type lists prettier in the generated code.

* Added a new 'tfop-eager-fallback' mode for bacckwards compatibility.

* 'tfop' compatibility fix.

* 'tfop' compatibility fix.

* 'tfop' compatibility fix.

* Bug fix.

* Added support for more '#tfop' attributes.

* Relaxed the 'TensorGroup' constraint for some types and improved the handling of input tensor lists for 'eager' mode.

* Added a more prominent warning about the 'execute' methods.

* Switched to 'eager' mode by default.

* Added calls to '_TFCOpSetDeviceFromScope'.

* Fixed a memory bug.

* Minor tweak.

* Fixed a bug related to type list attributes and input tensor lists.

* Bug fix related to number attributes.

* Disabled the status check for 'TFE_Op.addInputList'.

* Removed support for 'tfop' mode.

Author: eaplatanios