better docstrings (#144)

* first example of returns statement in docstring

* added a some return statements for pandas API

* last return statements in pandas input

* added returns to bdio docstrings

* few returns statements added to docstring

* finished docstrings for hadrons submodule

* also finished docstrings for json submodule

* finished misc submodule

* added returns in docstrings in openqQCD

* made some cosmetic chanes to dostrings

* added return nad return statement in docstring

* linting

* Improved docstrings of mpm, fits, roots, misc to have return statements

returns added for misc.py

returns added for mpm.py

reutrns added for fits.py

* linting...

* Some polishing of docstrings

pyerrors/input/utils.py

@@ -10,6 +10,11 @@ def check_idl(idl, che):
         idl of the current replicum
     che : list
         list of configurations to be checked against
+
+    Returns
+    -------
+    miss_str : str
+        string with integers of which idls are missing
     """
     missing = []
     for c in che:
@@ -22,3 +27,4 @@ def check_idl(idl, che):
         for i in missing[1:]:
             miss_str += "," + str(i)
         print(miss_str)
+    return miss_str