histoqc.ui: need to provide package_data via setup.py

It would be possible to switch to setup.cfg declarative config style,
if we'd specify the files individually, or add subfolder matching via
multiple single star globs, i.e.:
    *.css,
    */*.css,
    */*/*.css,
but unless all files are specified or
pypa/setuptools#1806 is implemented it
would probably cause confusion for a histoqc developer when they're
modifying the ui.

MANIFEST.in

@@ -6,3 +6,5 @@ recursive-exclude . *secrets*
 
 # ini config files
 include histoqc/config/*.ini
+# include user interface
+graft histoqc/ui/UserInterface

setup.py

@@ -1,23 +1,24 @@
-# This setup.py file is just needed to support editable installs via
-# `pip install -e .` and `python setup.py develop`
-#
-# NOTE:
-#   If you want an editable install `python setup.py develop` should
-#   not be used and you should always use `pip install -e .`
-#   But, it's almost guaranteed that some user will install via
-#   the former, and so let's make setuptools_scm work correctly
-#   in that case.
-#
+import glob
+import os.path
 from setuptools import setup
+
+# glob patterns in setup.cfg dont support recursive patterns
+# https://github.com/pypa/setuptools/issues/1806
+# so we have to do it in setup.py
+ui_files = [
+    os.path.relpath(f, "histoqc/ui/")
+    for f in glob.iglob("histoqc/ui/UserInterface/**/*", recursive=True)
+    if os.path.isfile(f)
+]
+
 setup(
-    # providing the settings is required for `python setup.py develop`
-    # to work correctly with setuptools_scm
-    # > set to `True` if we only allow `pip install -e .`
-    # ^^^ `True` requires a pyproject.toml with the below config!
     use_scm_version={
         # duplicated config from pyproject.toml; keep in sync
         "write_to": "histoqc/_version.py",
         "version_scheme": "post-release",
     },
-    setup_requires=['setuptools_scm']
+    setup_requires=['setuptools_scm'],
+    package_data={
+        'histoqc.ui': ui_files
+    }
 )