First taco

This release is the last commit on master before we swap the compiler machinery over to the second taco compiler. The first taco had several robustness issues, bugs and was too complex. It will therefore be replaced by the second taco after this release.

The second taco compiler does not change the user-facing Tensor and TensorBase classes so most users should not notice the difference. If, however, a user notices that first taco is better in some way then please let us know as we will then address this issue.

v0.1

First beta version, intended to be used by users that want some API stability as the master branch will be in flux.