Endless Difficulty Adjustment & Bug Fixes

[list] [*] We have reduced the Endless Wave 20 zombie health increase by half. [*] We have fixed a bug that would cause the players who joined Endless mode via matchmaking to see the story mode UI at the top of their screen. [*] Fixed a bug that caused highlighted attachments to display worse on the stats bar, despite having better values. This is just a bug fix, not the attachment overhaul patch which is coming at a later date. [/list]