Reject more invalid usernames from clients.

Specifically this should cover people connecting with a username of
"\u200C"
Fix #64: Allow [[cardname]] shortcut for card://
code cleanup
Server_CardZone speed optimisation
deadlock fix
changed user -> id_user in decklist_folders and decklist_files (issue #48)
added missing confirmation dialogue for remote folder deletion
added index to sql file
cmdDeckSelect fixed
fixed cmdDeckSelect (2)
added PasswordHasher::initialize() to make libgcrypt warnings go away
added Georgia to countries
fixed #101: added option to filter password protected games
Merge pull request #64 from Daenyth/issue-64

Allow `[[Cardname]]` as a synonym for `[card]cardname[/card]`
factored out duplicated code in [card] tag parsing
fixed #84: game creator couldn't re-join his game if the only buddies flag was set
Server_CardZone::getFreeGridColumn() now runs in O(log n), which should remove the performance bottleneck when processing insertCard(x = -1) commands on a large zone, e.g. createToken
server code cleanup
server crash fix
server deadlock fix