#449 #450

#449
- GalleryFragment.GalleryAdapterExt: added overridden method
checkNeedToLoadNextPage to return proper results for super item count
and super item position
- EndlessAdapter: added variation of checkNeedToLoadNextPage method with
the count parameter
- ImageFlowUtils.ItemGroupWrapper: added
- ImageFlowUtils: changed field itemGroups type
- ImageFlowUtils: added methdo getSuperItemPositionForGroupPosition
- ImageFlowUtils: modified getGroupItem method to return group list data
from ItemGroupWrapper

#450
- GalleryFragment.GalleryAdapterExt: added overridden method
deleteItemAt which notify imageFlowUtils about item deletion
- ImageFlowUtils: added new fields lastUsedWidth and lastIndex
- ImageFlowUtils: extracted method getRatio and replaced occurrences in
the calculateImageHeightResult, buildGroups and getSingleImageView
methods
- ImageFlowUtils: modified buildGroups method to do not repeat group
building work for not modified groups in case items are only appended
- ImageFlowUtils: added new methods onGroupsStructureModified