Fix bugs to allow multiple keymaps in one process

These were several initializations that were forgotten in the previous
memory leak fixes.

Now several xkb_desc's can coexist (relatively) peacefully.

Signed-off-by: Ran Benita <ran234@gmail.com>

[daniels: Only the atom.c is relevant with the new context API.]

src/atom.c

@@ -213,4 +213,5 @@ XkbcFreeAllAtoms(void)
     free(nodeTable);
     nodeTable = NULL;
     lastAtom = XKB_ATOM_NONE;
+    tableLength = 0;
 }