ModernBB 2.0 beta 2

This beta is focused on refining the improvements that we made during beta 1. With a redesigned admin index, Backstage, improvements against spambots, developer improvements and bugfixes.

#60 - Do not create sample data
#61 - Simplify upgrades
#70 - feature Redesign Admin Index
#82 - Review language files 2
#83 - Extensions menu item doesn't display "No plugins"
#84 - feature Add improvements against spam
#87 - Replace more PUN_ variables
#97 - Redesign H6 element
#98 - Rename the ashboard to Backstage
#100 - Admin forums render issue
#101 - Category page issue when no categories