doc: add figure caption top margin

also rename Fig. to Figure and add colon between Figure and the text:

(Figure X : Something) instead of (Fig. X Something)

Still one space to many, but better than no colon or margin at all

fixes #121

source/_static/css/theme_overrides.css

@@ -3,3 +3,9 @@ div.disclaimer {
     font-size: 10px;
     font-style: italic;
 }
+div.figure p.caption {
+    padding-top: 0.8em;
+}
+span.caption-number:after {
+    content: ": ";
+ }

source/conf.py

@@ -97,6 +97,12 @@ todo_include_todos = True
 
 # Figure numbering
 numfig = True
+numfig_format = {
+    'figure': 'Figure %s',
+    'table': 'Table %s',
+    'code-block': 'Listing %s',
+    'section': 'Section %s'
+}
 
 # -- Autodoc options ------------------------------------------------------