Ran flake8 and black linters, and other cleanup-related fixes.

Project now passes flake8 and black linter (also including more rst
cleanup). Moved latex related things to dedicated ``latex.py`` module,
and removed the ``makesheets -dF`` call from travis.

dungeonsheets/__init__.py

@@ -1,5 +1,13 @@
-__all__ = ('__version__', 'Character', 'weapons', 'features',
-           'character', 'race', 'background', 'spells')
+__all__ = (
+    "__version__",
+    "Character",
+    "weapons",
+    "features",
+    "mechanics",
+    "race",
+    "background",
+    "spells",
+)
 
 from dungeonsheets import background, features, race, spells, weapons, mechanics
 from dungeonsheets.character import Character
@@ -11,4 +19,4 @@ def read(fname):
     return open(os.path.join(os.path.dirname(__file__), fname)).read()
 
 
-__version__ = read('../VERSION')
+__version__ = read("../VERSION")