Multiselect works + interface handler

How multiselect works:

The main problem is that when multiselecting, editing becomes very hard
to control and monitor which item is been edited.

So not live editing while multiselect.

Transaction object has now IsEnabled property that if false disable the
user to use the ListBoxItem.

For ActionsList to be able to multiselect,, IsKeyboardFocusWithin
Trigger had to be less intrusive.
When changing the IsSelected property of an item, it becomes the ONLY
item that is selected.

So now IsKeyboardFocusWithin event needs to dealt by code that selects
the item. and not by trigger that fires even if the item is disabled!

ImportStage is now a global state and is not part of SelectListType.
Also the Multiselect is a new global state that mainly uses for
interface changes but can be also other code stuff.

New methods to deal with interface:
RealodTransactionPageInterface() Sets the top part of the page. the
decision is by Multiselect, ImportStage and ListType.

ReloadTransactionsActionsTotals()
Reloads the totals in the buttom. So the ImportStage editing problem is
fixed.

But for now there is not way to change the buttom.

For next:
Multi Edit for items using the separator.
Combine Items.