fix anaconda build (#421)

* fix anaconda build

* Added link for TKAgg

* Add matplotlib to requirements

We are pulling it in through scanpy, but since we are importing it directly we should include it explicitly

server/cli/launch.py

@@ -82,6 +82,10 @@ def launch(data, layout, diffexp, title, verbose, debug, obs_names, var_names,
 
     click.echo(f"[cellxgene] Loading data from {basename(data)}, this may take awhile...")
 
+    # Fix for anaconda python. matplotlib typically expects python to be installed as a framework TKAgg is usually
+    # available and fixes this issue. See https://matplotlib.org/faq/virtualenv_faq.html
+    import matplotlib as mpl
+    mpl.use('TkAgg')
     from server.app.scanpy_engine.scanpy_engine import ScanpyEngine
 
     args = {