Add missing FOV_SYMMETRIC_SHADOWCAST constant.

Also adds an import from constants to make it less bad when __all__
isn't updated correctly.

Fixes #101

Author: HexDecimal

CHANGELOG.rst

@@ -8,6 +8,8 @@ v2.0.0
 
 Unreleased
 ------------------
+Fixed
+ - Fixed missing `tcod.FOV_SYMMETRIC_SHADOWCAST` constant.
 
 11.18.1 - 2020-11-30
 --------------------

tcod/__init__.py

@@ -31,6 +31,7 @@
 )
 from tcod.console import Console  # noqa: F401
 from tcod.libtcodpy import *  # noqa: F4
+from tcod.constants import *  # noqa: F4
 from tcod.loader import __sdl_version__, ffi, lib  # noqa: F4
 
 try:
@@ -325,6 +326,7 @@
     "FOV_PERMISSIVE_8",
     "FOV_RESTRICTIVE",
     "FOV_SHADOW",
+    "FOV_SYMMETRIC_SHADOWCAST",
     "KEY_0",
     "KEY_1",
     "KEY_2",

tcod/libtcodpy.py

@@ -4667,6 +4667,7 @@ def _atexit_verify() -> None:
     "FOV_PERMISSIVE_8",
     "FOV_RESTRICTIVE",
     "FOV_SHADOW",
+    "FOV_SYMMETRIC_SHADOWCAST",
     "KEY_0",
     "KEY_1",
     "KEY_2",