Feature: Dynamic display in catalogue

Extension of https://github.com/azerothcore/azerothcore.github.io/issues/141

Let the user choose how many modules should be loaded per page by predefined values.

My suggestion:
Default 10
Let the user choose between 10, 15, 30, 50, 100

Start by reading the catalogue's current module-loading and page-display flow, along with the related issue #141. Locate where the per-page value is defined and how the module list is rendered. Done means users can choose 10, 15, 30, 50, or 100 modules per page, with 10 as the default.

Written by the indexing model from the issue text.