Add support for MacOS

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "py_slvs"]
 	path = py_slvs
 	url = https://github.com/realthunder/py_slvs.git
+[submodule "py_slvs_mac"]
+	path = py_slvs_mac
+	url = https://github.com/realthunder/py_slvs_mac.git

py_slvs_mac

@@ -0,0 +1 @@
+Subproject commit ff654b673c06bc5209522ba8a4dc2c5e9a812487

sys_slvs.py

@@ -1,6 +1,11 @@
 from .system import System, SystemBase, SystemExtension
 from .utils import syslogger as logger, objName
-from .py_slvs import slvs
+import platform
+
+if platform.system() == 'Darwin':
+    from .py_slvs_mac import slvs
+else:
+    from .py_slvs import slvs
 
 class SystemSlvs(SystemBase):
     __metaclass__ = System