Fix bug 2 by only allowing an undo in MODE_NORMAL.
Fix bug 2 by only allowing an undo in MODE_NORMAL.

deryakilic/solitaire-for-android,aeberh/solitaire-for-android,395651776/solitaire-for-android,arif-oployeelabs/solitaire-for-android,jsorchik/solitaire-for-android,fars/solitaire-for-android,Archrage/solitaire-for-android,Eeric5/solitaire-for-android,gorlok/solitaire-for-android,TrungDoan/solitaire-for-android,johsnel/solitaire-for-android,bonyhardian/solitaire-for-android,SlimZephyr/solitaire-for-android