Player info can now be accessed clientside

Player info is automatically synced to clients, they only get their own
info (due to possible exploitation, high network usage, unneeded etc).
Removed vending machine that was really close to another one. Added a
short description line to the top of each module. Removed unused
function round() in cl_changeteam. Slightly modified hud. Added
Achievements tab to menu GUI, acts like the old !achievements command
(#36). Achievement information now synced to clients
(achieved/progress). Switched sh_cash to fully use player info system
now that it's shared. Shop items are now automatically checked and only
show up in the list if they exist - If there are no valid items the tab
will display a warning message (fixes #81). Changed README.md to reflect
that addons are now recommended instead of required. Removed
!achievements (replaced by GUI).