Expanded achievement support + linux ndll updated

[Yanrishatum]

Added several methods for better achievement management:

• getAchievement(id:String):Bool - returns current achievement status.
• getAchievementDescription(id:String):String - returns UTF-8 string with achievement description field.
• getAchievementName(id:String):String - returns UTF-8 string with achievement name.
• isAchievementHidden(id:String):Bool - tells if achievement is flagged as hidden.
• getNumAchievements():Int - returns total amount of achievements.
• getAchievementAPIName(index:Int):String - returns achievement API name. Index should be in range [0...getNumAchievements].

All methods are documented in code.
Plus compiled Windows, Linux and Linux64 ndll binaries.

[larsiusprime]

Looks good to me. Thanks!