Implemented the keyword argument parser.

luprex/core/cpp/world-accessor.cpp

@@ -138,7 +138,7 @@ LuaDefine(tangible_build, "configtable",
     LuaRet database;
     LuaStack LS(L, config, classname, classtab, database, mt);
     
-    LS.checktable(config);
+    LS.checktable(config, "config");
     // Get the class of the new tangible.
     LS.rawget(classname, config, "class");
     eng::string err = LS.getclass(classtab, classname);
@@ -346,8 +346,13 @@ LuaDefine(tangible_find, "config",
     "|"
     "|   wholeplane: the name of the plane to scan in its entirety"
     "|"
-    "|It is valid to use 0.0 as the radius.  If you do so, then only"
-    "|objects at the exact center you specify will be found."
+    "|It is valid to use 0.0 as a radius.  For example, you could"
+    "|use shape='cylinder' and radiusz=0.0 to scan a flat"
+    "|circular area."
+    "|"
+    "|It is also valid to use math.huge (infinity) as a radius.  For"
+    "|example, you could use shape='cylinder' and radiusz=math.huge"
+    "|to scan an infinitely tall cylinder."
     "|"
     "|If you are making a 2D game, it works fine to set all object Z"
     "|coordinates to zero, and then do searches with centerz=0.0"
@@ -356,11 +361,11 @@ LuaDefine(tangible_find, "config",
     LuaArg config;
     LuaRet result;
     LuaStack LS(L, config, result);
+    LuaKeywordParser kw(LS, config);
     PlaneScan scan;
-    eng::string error = scan.configure(LS, config);
-    if (!error.empty()) {
-        luaL_error(L, "%s", error.c_str());
-    }
+    scan.configure(kw);
+    kw.check_unparsed_keywords();
+
     // When the configure routine sees the 'near' flag, it stores the tangible
     // ID, but not the center and plane, because doing so would require it to
     // know about world models.  We have to handle center and plane for 'near'