Add cmd.cpp cmd.h, MA_LENGTHOF to MA_Lengthof

core/cmd.h

@@ -0,0 +1,25 @@
+enum CmdDeclKind {
+    CmdDeclKind_Bool,
+    CmdDeclKind_List,
+    CmdDeclKind_Enum,
+};
+
+struct CmdDecl {
+    CmdDeclKind       kind;
+    S8_String         name;
+    S8_String         help;
+
+    bool *            bool_result;
+    Array<S8_String> *list_result;
+
+    int *             enum_result;
+    const char **     enum_options;
+    int               enum_option_count;
+
+};
+
+struct CmdParser {
+    int            argc;
+    char **        argv;
+    Array<CmdDecl> decls;
+};