v4.5.7

• Added a check for empty search queries (#53)
• Made query.pages a phub.Pages object, able to handle page indexes or slices.

# Unique page
first_page = query.pages[0]

# Iteration
for page in query.pages: ...

# Slicing
for page in query.pages[1:4]: ...

This change is a re-implementation of query item slices, removed in PHUB3 because some pages can have an inconsistent amount of items. Enhancment for #49.