Added commands to access player stats.

Loosely based on code from jcao219. New commands are "player", "p", "mystats", "me". The commands access existing stats stored in the game database (data.sqlite3).
Added game stats to database and "gamestats" command.

Added a game stats table to game DB to store wolf/village wins for
each game size. Added "gamestats" command to display stored stats.
Fix for multi-word roles.

Also added help definition for "mystats" command.
Changed behaviour of "gamestats" command.

"gamestats" without a parameter will list game totals for all game
sizes. The role parameter for player stats commands is now case
insensitive.
Fix for secure SQL operations.

Removed Python string operations from SQL operations.
Updated stats text. Player stats command checks for account.

Updated game text for stats commands. Fixed error with "mystats" help
string. Added additional check in player stats commands to find the
associated account before attempting to retrieve stats.
Added additional limits for "gamestats" parameters.

Added check to make sure the parameter is an integer between 4 and
var.MAX_PLAYERS.
Merge pull request #20 from brrr2/stats-pr

Adds player and game stats commands
Added "myrole" command.

A command to remind players of their role during games.
Added check for gun/bullets for "myrole" command.

Adds additional notification of gun/bullets if the player has them.
Minor change in the way messages are sent out for "myrole" command.
Removed redundant check in "myrole" command.
Added percentages to stats.

Added percentages when stats are outputted. Updated output for
"gamestats" command when no parameter is given.
Refactored some stats code.

Made update_roles_stats() and update_game_stats() a bit cleaner.
Added check for abnormal game stop before updating game stats.
Added get_player_totals(). Some code cleanup.

If the "player" or "mystats" command is called without a role,
then the bot will now list the total games that the player has
played in each role.