Added the convar
speedgun_multi_purchase (default 1) which allows you to set if the gun can be bought more than once per person
The convar updates on round changes.

Made the speedgun additive

I did not get a chance to test this, so please let me know if this causes issues

Renamed shared.lua to speedgun.lua (thought I had done that initially, turns out I didn't)

Added chat message to players who have been shot
Added SetRunSpeed, previously was not implemented due to having broken the addon prior

Initial release