added partitioned model fitting

Author: davidsebfischer

diffxpy/api/fit.py

@@ -1 +1 @@
-from diffxpy.fit import model, residuals
+from diffxpy.fit import model, residuals, partition

diffxpy/fit/__init__.py

@@ -1 +1 @@
-from .fit import model, residuals
+from .fit import model, residuals, partition

diffxpy/fit/external.py

@@ -1,3 +1,3 @@
 from diffxpy.testing.tests import _fit
-from diffxpy.testing.utils import parse_gene_names, parse_sample_description, parse_size_factors, \
+from diffxpy.testing.utils import parse_gene_names, parse_sample_description, parse_size_factors, parse_grouping, \
     constraint_system_from_star