Added multiple owners for cmd2/cmd2.py

Also:
- Added files to .gitignore for mypy plugin for PyCharm

Author: tleonhardt

.gitignore

@@ -20,3 +20,7 @@ htmlcov
 
 # mypy optional static type checker
 .mypy_cache
+
+# mypy plugin for PyCharm
+dmypy.json
+dmypy.sock

CODEOWNERS

@@ -16,6 +16,7 @@
 # cmd2 code
 cmd2/__init__.py        @tleonhardt @kotfu
 cmd2/arg*.py            @anselor
+cmd2/cmd2.py            @tleonhardt @kmvanbrunt @kotfu
 cmd2/constants.py       @kotfu
 cmd2/parsing.py         @kotfu @kmvanbrunt
 cmd2/pyscript*.py       @anselor