Magic Cube

Very important bugfix for an issue which probably has been the reason for many mysterious behaviours in the past: the JsonReader class cannot be a singleton! Convert it into a normal 'instanced' class.
With it being a singleton there's a major issue: when we create a new TwistyObject from a JSON file (by, for example, going to PurchaseActivity) and then we come back to the old object (by, for example, going back to the main RubikActivity) - then the JsonReader inside the old object has read the new JSON file and thus many of the 'abstract' methods in the old TwistyObject (for example getShortName()) all of the sudden start returning new values!

Purchase Pane: further progress.

Purchase Pane: further progress.

Purchase Pane: post-purchase dialogs.

Purchase Pane: post-purchase dialogs.

Purchase Pane: buttons (part2)

Purchase Pane: buttons

Fix marking objects as free.

Merge remote-tracking branch 'origin/master'

1. Conflicts:
2. src/main/java/org/distorted/objects/RubikObjectList.java

Fix marking objects as free.