Remove frontends/ directory.

It still had a bit of stale stuff.

frontends/README.md

@@ -1,17 +0,0 @@
-# NPComp - Frontends
-
-NPComp maintains in-tree frontends for various popular numeric-python based
-frameworks. In general these are:
-
-* Considered optional components
-* Target dialects maintained at the top-level of the project
-* Maintained in isolation so as to facilitate moving them out to dedicated
-  projects at an appropriate point of the lifecycle (i.e. if NPComp is
-  successful as a general purpose target for such frameworks, then it may
-  make sense to contribute/build each frontend to their respective up-stream
-  project).
-
-Frontends try to stylistically fit into the outer project except for when it
-is more clear/advantageous to align them with the conventions of the source
-project. This is approached on a case by case basis as needed. Deviations
-should be documented in a local style guide for the frontend.