All channel modes.

    #define SILC_CHANNEL_MODE_NONE          0x0000
    #define SILC_CHANNEL_MODE_PRIVATE       0x0001 /* private channel */
    #define SILC_CHANNEL_MODE_SECRET        0x0002 /* secret channel */
    #define SILC_CHANNEL_MODE_PRIVKEY       0x0004 /* channel has private key */
    #define SILC_CHANNEL_MODE_INVITE        0x0008 /* invite only channel */
    #define SILC_CHANNEL_MODE_TOPIC         0x0010 /* topic setting by operator */
    #define SILC_CHANNEL_MODE_ULIMIT        0x0020 /* user limit set */
    #define SILC_CHANNEL_MODE_PASSPHRASE    0x0040 /* passphrase set */
    #define SILC_CHANNEL_MODE_CIPHER        0x0080 /* sets cipher of the channel */
    #define SILC_CHANNEL_MODE_HMAC          0x0100 /* sets hmac of the channel */
    #define SILC_CHANNEL_MODE_FOUNDER_AUTH  0x0200 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_SILENCE_USERS 0x0400 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_SILENCE_OPERS 0x0800 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_CHANNEL_AUTH  0x1000 /* channel auth (signature) */