- was not used consistently before
- symbol names are expected to be valid C identifiers
- for complicated field names, the latex_name of field should be used

- small (length < 5) arrays with shape and stride information had to be
  memcpy'd to the GPU before every kernel call
- instead of passing the information as arrays, the single elements are
  passed
- leads to more function arguments, but simplifies GPU kernel calls

-> changes in all backends required

- not generic enough - does not work if there a multiple blocks

- removed warnings
- added flake8 as CI target

- test run again
- notebooks not yet

- single function to create kernel for specified target
- data type creation from string - reuse numpy functionality
- bugfixes in dot display

Fixed a severe bug. Renamed makePythonFunction of the llvm backend.
Deleted code duplicity.

Added LLVM: CodePrinter and a compiler
Updated data_types
Added tests
Added jupyter notebooks
Fixed bugs
Restructured transformation functions